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Help:Templates: Difference between revisions

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<languages/>
{{PD Help Page}}
{{PD Help Page}}
If you have standard texts you want to include on several pages, the MediaWiki template feature comes into play.
<translate><!--T:1--> If you have standard texts you want to include on several pages, the MediaWiki '''template''' feature comes into play.</translate>
<translate><!--T:116--> Unlike {{<tvar name=1>ll|Manual:Extensions</tvar>|extensions}} and {{<tvar name=2>ll|Help:Images</tvar>|media files}}, there is no central repository for templates.</translate>
<translate><!--T:260--> Templates can be newly written or, to save duplicating work already done, exported from another wiki e.g. Wikipedia, and then imported into the target wiki.</translate>


==Creation==
<translate>
Templates are standard wiki pages whose content is designed to be [[wikipedia:Transclusion|transcluded]] (embedded) inside other pages. Templates follow a convention that the name is prefixed with "<code>Template:</code>", assigning it to that namespace; besides this, you can [[Help:Starting a new page|create them like any other wiki page]].
== Basic usage == <!--T:261-->


The simplest use of templates is as follows. If you create a page called "Template:Welcome" with contents:
<!--T:3-->
Templates are standard wiki pages whose content is designed to be '''[[<tvar name=1>Special:MyLanguage/Transclusion</tvar>|transcluded]]''' (embedded) inside other pages. Templates follow a convention that the name is prefixed with "<tvar name=4><code>Template:</code></tvar>", assigning it to that [[<tvar name=2>Special:MyLanguage/Help:Namespaces</tvar>|namespace]]; besides this, you can [[<tvar name=3>Special:MyLanguage/Help:Starting a new page</tvar>|create them like any other wiki page]].


Hello! Welcome to the wiki.
<!--T:325-->
To transclude a template, you used double open & close curly brackets {{<tvar name=1>tmpl|0=<code><nowiki>{{</nowiki>$1<nowiki>}}</nowiki></code></tvar>|template name}}.


you'll have created your first template! If you then insert the code:
<!--T:4-->
The simplest use of templates is as follows: Create a page called <tvar name=1><code>Template:Welcome</code></tvar> with the content below:
</translate>
 
<translate><!--T:5--> Hello! Welcome to the wiki.</translate>
 
<translate>
<!--T:6-->
You have created your first template! Now, insert the code below in a new page:
</translate>


  <nowiki>{{Welcome}}</nowiki>
  <nowiki>{{Welcome}}</nowiki>


in any other page, when that page is viewed the text "Hello! Welcome to the wiki." will appear instead of <code><nowiki>{{Welcome}}</nowiki></code>. The template content is "transcluded" into the other page, i.e. it is integrated in the page.
<translate>
<!--T:8-->
When the new page is viewed, the text "Hello! Welcome to the wiki." will appear instead of <tvar name=1><code><nowiki>{{Welcome}}</nowiki></code></tvar>. The template content is '''transcluded''' into the other page, i.e., it is integrated in the page.


You can then insert <code><nowiki>{{Welcome}}</nowiki></code> at any point of any page where you wish to welcome someone. Suppose it is used in 100 pages. If you then change the template contents to:
<!--T:9-->
You can then insert <tvar name=1><code><nowiki>{{Welcome}}</nowiki></code></tvar> at any point of any page where you wish to welcome someone. Suppose it is used in 100 pages. If you then change the template contents to:
</translate>


  Hi there! Welcome to this wonderful wiki.
  <translate><!--T:10--> Hi there! Welcome to this wonderful wiki.</translate>


and revisit any of the 100 pages where the template was used, you'll see the new text instead of the original one. In this way, you have changed the content of 100 pages without editing them, because the template is transcluded into these pages.
<translate>
<!--T:11-->
And revisit any of the 100 pages where the template was used, you'll see the new text instead of the original one. In this way, you have changed the content of 100 pages without editing them, because the template is transcluded into these pages.


<!--T:12-->
This is the basic mechanism. There are several additional features of transclusion that enrich this mechanism and make templates very useful.
This is the basic mechanism. There are several additional features of transclusion that enrich this mechanism and make templates very useful.
</translate>


==Usage==
{{anchor|Usage}}
<translate>
== Ways to invoke a template == <!--T:262-->
 
<!--T:14-->
Templates can be used in other pages in these ways:
Templates can be used in other pages in these ways:


*<code><nowiki>{{Name}}</nowiki></code>, described above, 'transcludes' (i.e. includes a copy of) the content of the template (stored in the page <nowiki>[[Template:Name]]</nowiki>) whenever the page containing the template transclusion is fetched and displayed; i.e. if the template is later changed, the displayed transcluding page will automatically change too
<!--T:15-->
*<code><nowiki>{{subst:Name}}</nowiki></code> replaces that string with the contents of the template, in the source of the transcluding page, when you save that page; the copy of the template contents can then be edited normally (and separately from the original in the template page). ''Note'': don't use this if you are looking to continually propagate changes from the source template to the page(s) that references it.
* <code><nowiki>{{Name}}</nowiki></code> — As described above, this text (commonly referred to as a "template call") will be ''dynamically'' replaced by the content of the page titled Template:Name (a process called "transclusion") every time the page with the template call is '''loaded''' (i.e., viewed by a reader of the wiki).</translate> <translate><!--T:234--> Because the template call remains in the pages's source, any subsequent change to Template:Name will be seen on the page containing the template call.</translate> <translate><!--T:235--> Also, the page will be listed among those that "link to" the template.</translate>
*<code><nowiki>{{safesubst:Name}}</nowiki></code> was introduced in [[rev:61710]] to allow for substitution that doesn't break transclusion, see [[w:en:Help:Substitution#The safesubst: modifier]].
<translate>
*<code><nowiki>{{msgnw:Name}}</nowiki></code> includes the template in a form that displays it as raw wiki syntax (the way <code><nowiki>&lt;nowiki&gt;</nowiki></code> does) when the page containing it is fetched.
<!--T:16-->
* <code><nowiki>{{subst:Name}}</nowiki></code> — When this type of template call is used, it will be replaced by a ''static copy'' of the content of Template:Name as of the time the page containing the template call is '''saved'''.</translate> <translate><!--T:236--> That is, a copy of the contents of Template:Name will be ''substituted'' for the template call.</translate> <translate><!--T:237--> No link is maintained between the page and the template, so each can be edited further without affecting the other.</translate> <translate><!--T:238--> In effect, there is little difference between substituting the content in this way and simply typing it into the page's source "manually".</translate> <translate><!--T:263--> See <tvar name=1>{{ll|Help:Substitution}}</tvar> for more information.</translate>
<translate>
<!--T:17-->
* <code><nowiki>{{safesubst:Name}}</nowiki></code> — This was introduced to allow for recursive substitution in cases where templates contain calls to other templates or parser functions.</translate> <translate><!--T:239--> See <tvar name=1>{{ll|Help:Substitution}}</tvar> for more information.</translate>
<translate>
<!--T:18-->
* <code><nowiki>{{msgnw:Name}}</nowiki></code> — This displays the template content as raw wiki syntax (the way <tvar name=1>{{tag|nowiki|open}}</tvar> does) when the page containing it is viewed.</translate> <translate><!--T:264--> For example, <tvar name="1"><code><nowiki>{{msgnw:Template:Thankyou}}</nowiki></code></tvar> displays:</translate>


{{msgnw:Template:Thankyou/{{#ifexist:Template:Thankyou/{{PAGELANGUAGE}}|{{PAGELANGUAGE}}|en}}}}
<translate>
<!--T:19-->
In fact, an ordinary wiki page can also be used as a template, simply by specifying the namespace it resides in, so:
In fact, an ordinary wiki page can also be used as a template, simply by specifying the namespace it resides in, so:


*<code><nowiki>{{Template:Pagename}}</nowiki></code> includes <code><nowiki>[[Template:Pagename]]</nowiki></code>
<!--T:20-->
*<code><nowiki>{{Foo:Pagename}}</nowiki></code>       includes <code><nowiki>[[Foo:Pagename]]</nowiki></code>
* <code><nowiki>{{Template:Pagename}}</nowiki></code> transcludes the page titled Template:Pagename (equivalent to <code><nowiki>{{Pagename}}</nowiki></code>)</translate>
*<code><nowiki>{{:Pagename}}</nowiki></code>         includes <code><nowiki>[[Pagename]]</nowiki></code>
<translate>
**<code><nowiki>{{subst::Pagename}}</nowiki></code>   replaces itself with the contents of <code><nowiki>[[Pagename]]</nowiki></code>
<!--T:21-->
* <code><nowiki>{{Talk:Pagename}}</nowiki></code> transcludes the page titled Talk:Pagename</translate>
<translate>
<!--T:22-->
* <code><nowiki>{{:Pagename}}</nowiki></code> transcludes the page titled Pagename (i.e., in the main namespace)</translate>
<translate>
<!--T:23-->
** <code><nowiki>{{subst::Pagename}}</nowiki></code> substitutes the contents of the page titled Pagename
 
<!--T:24-->
If the specified namespace doesn't exist, the full title is assumed to be a template:
 
<!--T:25-->
* <tvar name=1><code><nowiki>{{Foo:Bar}}</nowiki></code></tvar> transcludes <tvar name=2>Template:Foo:Bar</tvar>
</translate>


If no such namespace exists, the full title is assumed to be a template:
<translate><!--T:265--> Regardless of what syntax is used, the name of the template can be relative to the current page</translate>
{{tmpl|0=<translate><!--T:266--> For example, if <tvar name="1"><code>{{((}}/$2{{))}}</code></tvar> is called on page <tvar name="2">$1</tvar>, it will transclude the page <tvar name="3">$1/$2</tvar>.</translate>
|1=<translate><!--T:267--> foo</translate>
|2=<translate><!--T:268--> bar</translate>
}}


*<code><nowiki>{{Foo:Bar}}</nowiki></code>           includes <code><nowiki>[[Template:Foo:Bar]]</nowiki></code>
<translate><!--T:269--> It can also be generated dynamically. </translate>
{{tmpl|0=<translate><!--T:270--> For example, <tvar name="1"><code>{{ {{((}}$1{{))}} }}</code></tvar> calls <tvar name="2">Template:$1</tvar> and interprets the result as the name of another template to call.</translate>
|1=<translate><!--T:271--> foo</translate>
}}


==Parameters==
<translate>
== Parameters == <!--T:26-->
 
<!--T:27-->
To enrich the mechanism of transclusion, MediaWiki allows parameters to be passed to a template when it is transcluded. Parameters allow the template to produce different contents or have different behaviors.
To enrich the mechanism of transclusion, MediaWiki allows parameters to be passed to a template when it is transcluded. Parameters allow the template to produce different contents or have different behaviors.


Suppose you wish to insert a little thank you note in the [[Help:Talk pages|talk page]] of other users, such as:
<!--T:28-->
Suppose you wish to insert a little thank you note in the [[<tvar name=1>Special:MyLanguage/Help:Talk pages</tvar>|talk page]] of other users, such as:


<!--T:29-->
{{Thankyou|all your effort|Me}}
{{Thankyou|all your effort|Me}}
The thank you note will have a reason (in this case, "all your effort") and a signature ("Me"). Your objective is that any user is able to thank any other user, for any reason whatsoever.


So that the note will look similar everywhere it is used, you can define a template called [[Template:Thankyou]], for example. Although the note should look similar whenever a user thanks another user, its specific contents (i.e. the reason and the signature) will be different. For that reason, you should pass them as parameters. If we ignore the remaining elements to format the box and place the image, the core content of the template will be this:
<!--T:30-->
The thank you note will have a reason (in this case, "all your effort") and a signature ("Me"). Your objective is for any user to be able to thank any other user, for any reason whatsoever.
</translate>


<pre><nowiki>'''A little thank you...'''
<translate><!--T:31--> So that the note will look similar everywhere it is used, you can define a template called <tvar name=tmpl>{{ll|Template:Thankyou}}</tvar>, for example.</translate>
<translate><!--T:183--> Although the note should look similar whenever a user thanks another user, its specific contents (i.e., the reason and the signature) will be different.</translate>
<translate><!--T:184--> For that reason, you should pass them as parameters.</translate>
<translate><!--T:185--> If we ignore the remaining elements to format the box and place the image, the core content of the template will be this:</translate>
 
<syntaxhighlight lang=moin>
<translate nowrap><!--T:32-->
'''A little thank you...'''
for {{{1}}}.
for {{{1}}}.
hugs, {{{2}}}</nowiki></pre>
hugs, {{{2}}}</translate>
</syntaxhighlight>
 
<translate>
<!--T:33-->
Notice the use of <tvar name=1><code><nowiki>{{{1}}}</nowiki></code></tvar> and <tvar name=2><code><nowiki>{{{2}}}</nowiki></code></tvar>. This is the way to identify, within templates, the parameters that will be passed in when the template is used. Note that, within the template, each parameter is surrounded by '''three''' braces: <tvar name=braces><code><nowiki>{{{ }}}</nowiki></code></tvar>. This is different from normal template name usage.


Notice the use of <code><nowiki>{{{1}}}</nowiki></code> and <code><nowiki>{{{2}}}</nowiki></code>. This is the way to identify, within templates, the parameters that will be passed in when the template is used. Note that, within the template, each parameter is surrounded by '''three''' braces: <code><nowiki>{{{ }}}</nowiki></code>. This is different from normal template name usage.
<!--T:34-->
When using the template on a page, you fill in the parameter values, separated by a "pipe" character (<tvar name=pipe><code>|</code></tvar>). MediaWiki allows parameters to be passed to the template in three ways: Anonymously, Numbered, and Named.


When using the template on a page, you fill in the parameter values, separated by a pipe char (<code>|</code>). MediaWiki allows parameters to be passed to the template in three ways.
=== Anonymous parameters === <!--T:35-->


=== Anonymous parameters ===
<!--T:36-->
To pass in anonymous parameters, list the values of those parameters sequentially:
To pass in anonymous parameters, list the values of those parameters sequentially:
</translate>
<translate><!--T:37--> <nowiki>{{Thankyou|all your effort|Me}}</nowiki></translate>


<nowiki>{{Thankyou|all your effort|Me}}</nowiki>
<translate>
In this case, template <code><nowiki>{{Thankyou}}</nowiki></code> receives parameters <code><nowiki>{{{1}}}=all your effort</nowiki></code> and <code><nowiki>{{{2}}}=Me</nowiki></code> and produces:
<!--T:38-->
In this case, the <code><nowiki>{{Thankyou}}</nowiki></code> template receives parameters <code><nowiki>{{{1}}}=all your effort</nowiki></code> and <code><nowiki>{{{2}}}=Me</nowiki></code>, producing:


<!--T:39-->
{{Thankyou|all your effort|Me}}
{{Thankyou|all your effort|Me}}


Inverting the order of the parameters:
<!--T:40-->
The order in which anonymous parameters are passed in is crucial to its behavior. Reversing the order of the parameters, like so:
</translate>


  <nowiki>{{Thankyou|Me|all your effort}}</nowiki>
  <translate><!--T:41--> <nowiki>{{Thankyou|Me|all your effort}}</nowiki></translate>


causes template <code><nowiki>{{Thankyou}}</nowiki></code> to receive parameters <code><nowiki>{{{1}}}=Me</nowiki></code> and <code><nowiki>{{{2}}}=all your effort</nowiki></code> and inverts the result:
<translate>
<!--T:42-->
would produce this result:


<!--T:43-->
{{Thankyou|Me|all your effort}}
{{Thankyou|Me|all your effort}}
So, the order in which anonymous parameters are passed in is crucial to its behaviour.
</translate>


=== Numbered parameters ===
{{note|1=<translate><!--T:44--> Identifying parameters by order (with <tvar name=1><code><nowiki>{{{1}}}</nowiki></code></tvar>, etc.) works ''only'' with anonymous parameters.</translate> <translate><!--T:208--> Any parameters identified by name, as shown below, will not be accessible to the template using ordinal numbers.</translate>}}
 
{{note|1=<translate><!--T:120--> If an equal sign appears inside the argument to an anonymous template parameter, that parameter may be misinterpreted as a [[<tvar name=1>#Named parameters</tvar>|named parameter]] (which is explained below in this document) treating the text before the equal sign as the parameter name and the text after it as the argument value.</translate> <translate><!--T:121--> This is a common problem when you need to include an external link, or an HTML element with attributes (see <tvar name=1>{{task|T16235}}</tvar>).</translate> <translate><!--T:122--> The workaround is to use named parameters instead, or even numbered parameters as explained in the following section.</translate>}}
 
<translate>
=== Numbered parameters === <!--T:45-->
 
<!--T:46-->
To pass in parameters by number, identify each parameter when passing it:
To pass in parameters by number, identify each parameter when passing it:
</translate>


  <nowiki>{{Thankyou|2=Me|1=your friendship}}</nowiki>
  <translate><!--T:47--> <nowiki>{{Thankyou|2=Me|1=your friendship}}</nowiki></translate>


<translate>
<!--T:48-->
This time, template <code><nowiki>{{Thankyou}}</nowiki></code> receives parameters <code><nowiki>{{{1}}}=your friendship</nowiki></code> and <code><nowiki>{{{2}}}=Me</nowiki></code>, though they have been supplied in inverse order, and produces:
This time, template <code><nowiki>{{Thankyou}}</nowiki></code> receives parameters <code><nowiki>{{{1}}}=your friendship</nowiki></code> and <code><nowiki>{{{2}}}=Me</nowiki></code>, though they have been supplied in inverse order, and produces:
<!--T:191-->
{{Thankyou|2=Me|1=your friendship}}
{{Thankyou|2=Me|1=your friendship}}
</translate>
{{note|1=<translate><!--T:176--> This may also be useful when any of the numbered parameters contains an "<tvar name=1>=</tvar>" sign.</translate>}}


=== Named parameters ===
;<translate><!--T:177--> Examples:</translate>
The third way of passing parameters is by name, instead of numbers. In this case, the template contents would be changed to:


<pre><translate nowrap><!--T:207--> {{Thankyou|1=adding “=”|2=Me}}</translate></pre>
<translate><!--T:178--> produces:</translate>
<translate><!--T:179--> {{Thankyou|1=adding “=”|2=Me}}</translate>
{{warning|1=<translate><!--T:180--> This also requires numbering each other parameter.</translate>}}
<translate>
=== Named parameters === <!--T:49-->
<!--T:50-->
The third way of passing parameters is by name instead of numbers.  In this case, the template contents would be changed to:
<!--T:51-->
<pre><nowiki>'''A little thank you...'''
<pre><nowiki>'''A little thank you...'''
for {{{reason}}}.
for {{{reason}}}.
hugs, {{{signature}}}</nowiki></pre>
hugs, {{{signature}}}</nowiki></pre>


<!--T:52-->
Within the template, we use <code><nowiki>{{{reason}}}</nowiki></code> and <code><nowiki>{{{signature}}}</nowiki></code> to identify each parameter, instead of a number. To pass these parameters by name, identify each parameter when passing it:
Within the template, we use <code><nowiki>{{{reason}}}</nowiki></code> and <code><nowiki>{{{signature}}}</nowiki></code> to identify each parameter, instead of a number. To pass these parameters by name, identify each parameter when passing it:
</translate>


  <nowiki>{{Thankyou|signature=Me|reason=being who you are}}</nowiki>
  <translate><!--T:53--> <nowiki>{{Thankyou|signature=Me|reason=being who you are}}</nowiki></translate>


<translate>
<!--T:54-->
In this case, template <code><nowiki>{{Thankyou}}</nowiki></code> receives parameters <code><nowiki>{{{reason}}}=being who you are</nowiki></code> and <code><nowiki>{{{signature}}}=Me</nowiki></code> and produces:
In this case, template <code><nowiki>{{Thankyou}}</nowiki></code> receives parameters <code><nowiki>{{{reason}}}=being who you are</nowiki></code> and <code><nowiki>{{{signature}}}=Me</nowiki></code> and produces:


<!--T:55-->
{{Thankyou|signature=Me|reason=being who you are}}
{{Thankyou|signature=Me|reason=being who you are}}
<!--T:181-->
Named parameters are '''case-sensitive''', so:
<!--T:151-->
<pre><nowiki>{{Thankyou|signature=Me|Reason=being who you are|reason=being case-sensitive}}</nowiki></pre>
<!--T:152-->
produces:
<!--T:192-->
{{Thankyou|signature=Me|Reason=being who you are|reason=being case-sensitive}}
<!--T:153-->
The advantage of using named parameters in your template, besides also being flexible in the order parameters can be passed, is that it makes the template code much easier to understand if there are many parameters.
The advantage of using named parameters in your template, besides also being flexible in the order parameters can be passed, is that it makes the template code much easier to understand if there are many parameters.


=== Default values ===
<!--T:272-->
If you transclude a template that expects parameters, but do not provide them, in this way:
Spaces and newlines are automatically stripped from the start and end of named parameter names and values, but are preserved in unnamed parameters.


<nowiki>{{Thankyou}}</nowiki>
=== Mixing named and unnamed parameters === <!--T:273-->


<!--T:274-->
If the template supports it, both kinds of parameters can be used in one call.
</translate>
For example, <code><nowiki>{{Thankyou|supporting both parameter types|signature=Me}}</nowiki></code> results in:
{{Thankyou|supporting both parameter types|signature=Me}}
Be careful when doing this, because it can result in conterintuitive results as unnamed parameter counts are based only on the unnamed parameters, not the named parameters. For example,  <code><nowiki>{{Thankyou|Me|reason=supporting both parameter types}}</nowiki></code> results in:
{{Thankyou|Me|reason=supporting both parameter types}}
The template is coded to prefer the named parameter for the reason over the unnamed parameter, resulting in the "Me" being lost and no signature being given. This results in a default value of {{{2}}} being shown, as explained below.
<translate>
=== Default values === <!--T:56-->
</translate>
{{see also|Manual:Advanced templates#Use of parameter default}}
<translate>
<!--T:57-->
If you transclude a template that expects parameters, but do not provide their arguments, in this way:
</translate>
<translate><!--T:58--> <nowiki>{{Thankyou}}</nowiki></translate>
<translate>
<!--T:59-->
in the numbered parameters example above you would get the following:
in the numbered parameters example above you would get the following:
</translate>


{{Thankyou}}
{{Thankyou}}
Since no parameters were passed in, the template presents the parameters themselves, instead of their respective values. In these cases, it may be useful to define ''default'' values for the parameters, i.e. values that will be used if no value is passed in. For example, if the template contents are changed to:


<pre><nowiki>'''A little thank you...'''
<translate>
<!--T:61-->
Since no arguments were passed in, the template presents the parameters themselves, instead of their respective values. In these cases, it may be useful to define ''default'' values for the parameters, i.e. values that will be used if no value is passed in. For example, if the template contents are changed to:
</translate>
 
<syntaxhighlight lang=moin>
<translate nowrap><!--T:62-->
'''A little thank you...'''
for {{{reason|everything}}}.
for {{{reason|everything}}}.
hugs, {{{signature|Me}}}</nowiki></pre>
hugs, {{{signature|Me}}}</translate>
</syntaxhighlight>
 
<translate>
<!--T:63-->
then <code><nowiki>{{{reason|everything}}}</nowiki></code> defines that if no argument is provided for parameter <code>{{{reason}}}</code>, then the value <code>everything</code> will be used. Similarly, <code><nowiki>{{{signature|Me}}}</nowiki></code>, defaults parameter <code>{{{signature}}}</code> to value <code>Me</code>. Now, transcluding the template again without passing any argument results in the following:
</translate>


then <code><nowiki>{{{reason|everything}}}</nowiki></code> defines that if no parameter <code>{{{reason}}}</code> is provided, then the value <code>everything</code> will be used. Similarly, <code><nowiki>{{{signature|Me}}}</nowiki></code>, defaults parameter <code>{{{signature}}}</code> to value <code>Me</code>. Now, transcluding the template again without passing any parameter, results in the following:
<!-- strictly speaking, this example is false, because the template call was changed to obtain the desired effect - but the effect is the same if the template is defined as described -->
<!-- strictly speaking, this example is false, because the template call was changed to obtain the desired effect - but the effect is the same if the template is defined as described -->
<translate>
<!--T:146-->
{{Thankyou|reason=everything|signature=Me}}
{{Thankyou|reason=everything|signature=Me}}
</translate>
{{note|1=<translate><!--T:231--> The value of a parameter can be an empty string.</translate> <translate><!--T:232--> For example, in <tvar name=1><code><nowiki>{{foo|bar=}}</nowiki></code></tvar> or <tvar name=2><code><nowiki>{{foo|bar=|baz=qux}}</nowiki></code></tvar>, the <tvar name=5><code>foo</code></tvar> template considers the <tvar name=3><code>bar</code></tvar> parameter to be <tvar name=4><code>""</code></tvar>.</translate> <translate><!--T:233--> This is different from omitting the parameter altogether, which leaves it undefined and triggers the default value mechanism described above.</translate>
}}
{{note|1=If you need to treat an empty string the same way as a missing parameter, you can use a conditional operator through an extension like [[Extension:ParserFunctions|ParserFunctions]]. For instance, <code><nowiki>{{#if:{{{1|}}}|{{{1|}}}|undefined}}</nowiki></code> returns undefined if the parameter is either undefined or empty, while <code><nowiki>{{{1|undefined}}}</nowiki></code> does so only if the parameter is undefined.
}}
<translate><!--T:194--> Often default values are used to specify alternate names of parameters.</translate>
<translate><!--T:195--> For example, if you have <tvar name=1><code><nowiki>{{{a|{{{b|}}} }}}</nowiki></code></tvar>, the template will first look for a parameter named "<tvar name=2>a</tvar>".</translate>
<translate><!--T:196--> If it is not set, it will use the parameter named "<tvar name=1>b</tvar>".</translate>
<translate><!--T:197--> If neither "<tvar name=1>a</tvar>" nor "<tvar name=2>b</tvar>" is set, it will output nothing.</translate>
=== Passing parameters to other templates ===
If raw parameter syntax is generated by the above template call, and then passed through to another template, it is '''not''' interpreted as a parameter. This means that {{Tl|thankyou2}}, which just calls {{tl|thankyou}} with no parameters, does not work: {{tlx|thankyou2|everything|me}} -> {{thankyou2|everything|me}}.
You instead need to explicitly pass the parameter to the other template, i.e if {{tl|thankyou3}} contains
<syntaxhighlight lang="wikitext">
{{thankyou|{{{1}}}|{{{2}}}}}}
</syntaxhighlight>
then {{tlx|thankyou3|everything|me}} -> {{thankyou3|everything|me}} works properly.
This example does not [[#Empty vs undefined parameters|preserve emptiness vs. undefinedness in parameter values]] - you would need more complicated syntax if you wanted to do that.
<translate>
=== Empty vs undefined parameters === <!--T:275-->
</translate>
<translate><!--T:276--> The <tvar name=1><code><span style="color:red">&#123;&#123;</span>t2demo<span style="color:red">&#124;&#124;</span> <span style="color:green">a</span> <span style="color:red">&#125;&#125;</span></code></tvar> (refer to <tvar name="2">{{tl|t2demo}}</tvar> ), with a double pipe, sets the first parameter to an '''empty''' string instead of leaving it undefined.</translate>
<translate><!--T:277--> It produces the output <tvar name=1><code>start--middle- a -end</code></tvar>, similar to how <tvar name=2><code><span style="color:red">&#123;&#123;</span>t2demo<span style="color:red">&#124;</span>1=<span style="color:red">&#124;</span>2= <span style="color:green">a</span> <span style="color:red">&#125;&#125;</span></code></tvar> results in <tvar name=3><code>{{t2demo|1=|2={{#tag:font| a |color="green"|style="color:green"}}}}</code></tvar>.</translate>
<translate><!--T:278--> On the other hand, explicitly setting the parameter "2" to "a," results in the first unnamed parameter being left '''undefined''':</translate>
<translate>
<!--T:279-->
<tvar name="1"><span style="color:red">&#123;&#123;</span>t2demo<span style="color:red">&#124;</span>2= <span style="color:green">a</span> <span style="color:red">&#125;&#125;</span></tvar> results in <tvar name="2">{{t2demo|2={{#tag:font| a |color="green"|style="color:green"}}}}</tvar>
<!--T:280-->
If the second parameter should not be trimmed, it must be unnamed.
<!--T:281-->
Therefore, you can assign an empty string to the first parameter, but you cannot leave it undefined.
==== Making emptiness and undefinedness equivalent ==== <!--T:282-->
<!--T:283-->
Good template coding practices result in passing an empty string to a parameter working the same as not assigning any value.
This makes things easier and more consistent.
<!--T:284-->
For example, using <tvar name="1"><code>p=</code></tvar> can show that a template has a parameter "p" that doesn't have a value yet.
<!--T:285-->
To make an empty string and an undefined value equivalent, use the following approaches:
</translate>
* <translate><!--T:286--> Use <tvar name="1"><code><nowiki>{{{p|}}}</nowiki></code></tvar> exclusively instead of <tvar name="2"><code>{{{p}}}</code></tvar> or <tvar name="3"><code>{{{p|q}}}</code></tvar> where "q" is a non-empty value.</translate>
* <translate><!--T:287--> Use conditional checks like <tvar name="1"><code><nowiki>{{#if:{{{p|}}}|..{{{p}}}..|..}}</nowiki></code></tvar>, to ensure <tvar name="2"><code>{{{p}}}</code></tvar> is only used when it has a value.</translate>
If for some reason you want to treat undefined parameters differently from empty parameters or any other possible value you can compare the same parameter twice with different defaults, i.e <code><nowiki>{{#ifeq:{{{foo|bar}}}|{{{foo|baz}}}|parameter is defined|parameter is undefined}}</nowiki></code>.
<translate>
=== Using equals signs in unnamed parameters === <!--T:288-->
</translate>
<translate><!--T:289--> Unnamed parameters can include equals signs, but this must be done indirectly.</translate>
<translate><!--T:290--> Here are some methods using <tvar name="1">[[template:T1demo]]</tvar>:</translate>
; <translate><!--T:291--> Default Value for Undefined Parameter</translate>
<translate><!--T:292--> Assign a default value to an undefined parameter:</translate>
<code><nowiki>{{T1demo|{{{1| a=b }}}}}</nowiki></code>
<translate><!--T:293--> This renders as:</translate> <code>{{T1demo|{{{1| a=b }}}}}</code>.
; <translate><!--T:294--> Using the <tvar name="1"><code><nowiki>{{=}}</nowiki></code></tvar> parser function</translate>
<translate><!--T:295--> Use a parser function that safely includes an equals sign:</translate>
<code><nowiki>{{T1demo| a{{=}}b }}</nowiki></code>
<translate><!--T:296--> This renders as:</translate> <code>{{T1demo| a{{=}}b }}</code>.
; <translate><!--T:297--> HTML Entities</translate>
<translate><!--T:298--> Replace the equals sign with an HTML entity for display:</translate>
<code><nowiki>{{T1demo| a&#61;b }}</nowiki></code>
<translate><!--T:299--> This renders as:</translate> <code>{{T1demo| a&#61;b }}</code>.
<translate>
<!--T:300-->
This renders correctly without affecting the other parameters.
=== Handling unmatched curly and square brackets === <!--T:301-->
<!--T:302-->
Unmatched curly brackets (<tvar name=1><code><nowiki>{{</nowiki></code></tvar>, <tvar name="2"><code>}}</code></tvar>) or square brackets (<tvar name=3><code><nowiki>[[</nowiki></code></tvar>, <tvar name="4"><code>]]</code></tvar>) must be inside nowiki tags or use HTML entities:
</translate>
* <translate><!--T:303--> Rendering curly brackets have two options:</translate>
** <translate><!--T:304--> Use <tvar name="1"><code><nowiki>&lt;nowiki>{{</nowiki></nowiki></code></tvar> or <tvar name="2"><code>&amp;#123;</code></tvar> for <tvar name="3"><code>{</code></tvar></translate>
** <translate><!--T:305--> Use <tvar name="1"><code><nowiki>&lt;nowiki>}}</nowiki></nowiki></code></tvar> or <tvar name="2"><code>&amp;#125;</code></tvar> for <tvar name="3"><code>}</code></tvar>.</translate>
* <translate><!--T:306--> Use <tvar name="1"><code>&amp;#91;</code></tvar> for <tvar name="2"><code>&#91;</code></tvar> and <tvar name="3"><code>&amp;#93;</code></tvar> for <tvar name="4"><code>]</code></tvar>.</translate>
<translate>
<!--T:307-->
Below are some examples:
</translate>
; <translate><!--T:308--> Unmatched curly brackets</translate>
<code><nowiki>{{T1demo| &lt;nowiki>{{&lt;/nowiki>content&lt;nowiki>}}&lt;/nowiki> }}</nowiki></code>
<translate><!--T:309--> This correctly renders the braces without breaking the template.</translate>
; <translate><!--T:310--> Unmatched square brackets</translate>
<code><nowiki>{{T1demo| text &#91;link&#93; more text }}</nowiki></code>
<translate><!--T:311--> This correctly renders the braces without breaking the template.</translate>
<translate><!--T:312--> This renders as:</translate>
<code>{{T1demo| text &#91;link&#93; more text }}</code>
<translate>
<!--T:313-->
Unmatched pairs not placed in nowiki tags either prevent template expansion or are taken as closing braces for the template call.
<!--T:314-->
Below are some examples:
</translate>
<code><nowiki>{{T1demo|abc]]def[[ghi}}</nowiki></code>
<translate>
<!--T:315-->
This will not expand correctly because of unmatched brackets.
<!--T:316-->
The correct use:
</translate>
<code><nowiki>{{T1demo|abc&lt;nowiki>]]&lt;/nowiki>def&lt;nowiki>[[&lt;/nowiki>ghi}}</nowiki></code>
<translate><!--T:317--> This renders as:</translate>
<code>{{T1demo|abc<nowiki>]]</nowiki>def<nowiki>[[</nowiki>ghi}}</code>
==== Template-generated brackets ====
An alternate technique for passing arguments with unmatched brackets is to wrap them in another template. In that situation, (which exists with {{tl|((}} and {{tl|))}}) on this wiki), the unmatched brackets will be rendered literally, and not decoded as another template call. For example:
<syntaxhighlight lang="wikitext">
{{t1demo|{{((}}t1demo{{))}}}}
</syntaxhighlight>
results in:
{{t1demo|{{((}}t1demo{{))}}}}
When [[Help:Substitution|substituting]] a template, template inclusions are parsed once when the subst happens (with the same caveats explained above) and then a second time when rendering the resulting wikitext. For example:
<syntaxhighlight lang="wikitext">
{{subst:((}}t1demo|foo}}
</syntaxhighlight>
will expand on save to:
<syntaxhighlight lang="wikitext">
{{((}}t1demo|foo}}
</syntaxhighlight>
which will then render as:
{{t1demo|foo}}
If the wikitext generated via the first subst itself includes "subst:" syntax it will not be processed on the same save, but may be on the next save. This technique may be used to implement [[Manual:Recursive conversion of wikitext|recursive substitutions]] that take multiple saves to evaluate.
=== Using pipes in parameter values ===
A parameter value cannot contain a pipe character (|), because it would be interpreted as the end of that parameter and the start of the next parameter.
This can be worked around by using the {{ll|Help:Parser function|parser function}} <code><nowiki>{{!}}</nowiki></code>, or the HTML entity &amp;124;.
The two methods of doing this have slightly different behavior, which can be relevant in some corner cases like when a template is producing [[Help:Tables|wikitable]] syntax.
Example:
<code><nowiki>{{T1demo|abc|def}}</nowiki></code>
produces:
{{T1demo|abc|def}}
The "def" doesn't display because it is treated as part of another unnamed parameter, which the template does not use.
<code><nowiki>{{T1demo|abc{{!}}def}}</nowiki></code>
produces:
{{T1demo|abc{{!}}def}}
The "def" displays properly.
<code><nowiki>{{T1demo|abc&#124;def}}</nowiki></code>
produces:
{{T1demo|abc&#124;def}}
The "def" displays properly again.
=== Formatting template calls using extra parameters ===
Since templates ignore parameters they are passed but do not handle specifically, they can be used as a way of a adding extra whitespace or unused content to the template call.
For example:
<syntaxhighlight lang="wikitext">
{{template name|foo|bar|baz|mumble|quux}}
</syntaxhighlight>
is equivalent to, assuming the template doesn't recognize SPACEN as a parameter name:
<syntaxhighlight lang="wikitext">
{{template name|SPACE1=
|foo|SPACE2=
|bar|SPACE3=Random stuff
|baz|SPACE4=
  |mumble|SPACE5=
  quux
}}
</syntaxhighlight>
It is also possible to use the same name for each spacer (often the empty string), but this will populate [[:Category:Pages using duplicate arguments in template calls]], which many wikis prefer to keep empty to catch instances of user error.
This can be used to make the template render in a way similar to its output, like showing each row of [[w:Template:Chess position]] on its own like to make the wikitext also look like a chessboard.
== Tracking parameter usage ==
{{see also|Help:Tracking categories}}
It may be wise for a template to add a link or category to a page if a certain parameter or combination of parameters is used, to make if possible to easily determine what pages are using a given parameter, and thus what the impacts of changing that parameter in the template would be.
<translate>
== Evaluation process == <!--T:198-->
</translate>
{{Note|1=<translate><!--T:199--> This is an advanced topic which you can skip unless you need it.</translate>}}
<translate><!--T:200--> Generally speaking, template parameters are substituted into the template after tokenization, but as is.</translate>
<translate><!--T:201--> They are not evaluated until they are used.</translate>
<translate><!--T:202--> This has a few consequences:</translate>
# <translate><!--T:213--> If you have a <tvar name=1><code>Template:Start</code></tvar> containing <tvar name=2><code><nowiki>{{mytemplate</nowiki></code></tvar>, and a <tvar name=3><code>Template:End</code></tvar> containing <tvar name=4><code><nowiki>|foo=bar}}</nowiki></code></tvar>, and put <tvar name=5><code><nowiki>{{start}}{{end}}</nowiki></code></tvar> on a page, ''mytemplate'' isn't transcluded, because tokens like "|" cannot be added by a template and keep their special meaning in templates.</translate> <translate><!--T:203--> You can still use templates to control the name of a parameter or template, but you cannot split a template call amongst multiple templates.</translate>
# '''<translate><!--T:204--> Dead-code elimination:</translate>''' <translate><!--T:214--> If you make a template call like <tvar name=1><code><nowiki>{{foo|{{DISPLAYTITLE:Bar}} }}</nowiki></code></tvar>, and <code>Template:Foo</code> does not contain <tvar name=2><nowiki>{{{1}}}</nowiki></tvar>, then the <tvar name=3><code>DISPLAYTITLE</code></tvar> is not used, since it is only evaluated when needed, and there is no parameter to substitute it into, so it is never evaluated.</translate> <translate><!--T:215--> This usually comes into play when using <tvar name=3>{{ll|Extension:ParserFunctions}}</tvar>, and can be especially noticed when used in combination with the <tvar name=2><code><nowiki>int:</nowiki></code></tvar> magic word that varies by user language.</translate> <translate><!--T:318--> This isn't perfect, and in some cases even if the result of expanding a template is not used (because it is part of an if statement condition, for example), the process of evaluating it can still have [[w:Side effect (computer science)|side effects]].</translate> <translate><!--T:319--> For example, any {{<tvar name=1>ll|Help:Links</tvar>|links}} produced or other templates used will still be added to <tvar name=2>[[Special:WhatLinksHere]]</tvar> even if they are not displayed.</translate>


===Control template inclusion===
Template parameters are [[w:pass by value|pass by value]], which means a template cannot modify its arguments. Parameters are treated as [[w:Associative array|associative array]], and parameter names are evaluated before parameter values. If the same parameter name is given more than once (either as named or unnamed), only the last instace is used, and the page is added to [[:Category:Pages using duplicate arguments in template calls]].  
By default, the whole content of a template will be processed and displayed both when the template page is being viewed directly and when the template is being included in another page. However, you can control template inclusion by the use of <code><nowiki><noinclude></nowiki></code> and
<code><nowiki><includeonly></nowiki></code> tags.


Anything between <code><nowiki><noinclude></nowiki></code> and <code><nowiki></noinclude></nowiki></code> will be processed and displayed only when the template's page is being viewed directly, and will not be processed and displayed when it is included in another page. The application of this is to do things to the template page that should not be similarly done to the pages where it is included:
<translate><!--T:216--> Template calls starting with the magic word <tvar name=1><code>subst:</code></tvar> or <tvar name=2><code>safesubst:</code></tvar> are evaluated in a separate first pass that only happens at save time, along with <tvar name=3><nowiki>~~~~</nowiki></tvar> and links using the [[<tvar name=4>Special:MyLanguage/pipe trick</tvar>|pipe trick]].</translate>
<translate><!--T:217--> If they cannot be evaluated during the first pass, <tvar name=1><code>subst:</code></tvar> calls are ignored, and <tvar name=2><code>safesubst:</code></tvar> are treated as if a normal template.</translate>


* [[Help:Categories|Categorising]] the template.
<translate><!--T:205--> Many but not all parser functions, parser tags and trancluded special pages are not directly included like templates but instead are replaced by a "strip marker".</translate>
* Placing in the template [[Help:Links#Interlanguage links|interlanguage links]] to similar templates in other languages.
<translate><!--T:206--> This means you cannot manipulate the results with parser functions like <tvar name=1>padleft:</tvar> or similar functions from extensions, as they see the strip marker instead of the result of the parser function.</translate>
* Presenting explanatory text about how to use the template.


Anything between <code><nowiki><includeonly></nowiki></code> and <code><nowiki></includeonly></nowiki></code> will be processed and displayed only when the page is being included, and will not be processed and displayed when the template page is being viewed directly. The application of this is to do things in the pages where the template is included that you do not want to be similarly done in the template page:
<translate>
=== Recursion in templates === <!--T:149-->
</translate>
<translate><!--T:124--> Including a template in itself won't throw MediaWiki into infinite recursion.</translate>
<translate><!--T:125--> MediaWiki will stop the recursion with the template's name in bold.</translate>
<translate><!--T:126--> For example, if the content of Template:Aaaa is <tvar name=code><code>a <nowiki>{{Aaaa}}</nowiki> z</code></tvar>, it'll display "<tvar name=result>a a <span class="error">Template loop detected:  '''Template:Aaaa'''</span> z z</tvar>".</translate>


* [[Help:Categories|Categorising]] only the pages where the template is included. Note that when you change the categories applied by a template in this fashion, the categorization of all the pages where that template is included may not be updated until some time later: this is handled by the {{mediawiki|Manual:Job queue|job queue}}. To force the re-categorisation of a particular page, open the page for edit and save it without changes.
<translate><!--T:219--> This safeguard precludes a potentially useful template idiom where a template self-normalizes its own calling arguments.</translate>
* Ensuring that the template's code is not executed when viewing the template page itself. Normally this is because it isn't receiving any parameters and its execution without parameters has an undesired aspect.
<translate><!--T:220--> In this forbidden example <tvar name=1><code>template:d</code></tvar> can either be called <tvar name=2><code><nowiki>{{d|20200311}}</nowiki></code></tvar> or <tvar name=3><code><nowiki>{{d|y=2020|m=3|d=11}}</nowiki></code></tvar>.</translate>
<translate><!--T:221--> If called in the first manner, it recurses into itself with the second argument structure (obtained using string parser functions), which then follows a unified processing path.</translate>


Of course, everything outside <code><nowiki><noinclude></nowiki></code> and
<syntaxhighlight lang="wikitext">
<code><nowiki><includeonly></nowiki></code> tags is processed and displayed both when the template page is being viewed directly and when the template is being included in another page.
{{#if:{{{1|}}}|{{d|y={{#sub:{{{1}}}|0|4}}|m={{#sub:{{{1}}}|4|2}}|d={{#sub:{{{1}}}|6|2}}}}|<!-- processing path with arguments y,m,d regardless of original call pattern -->}}
</syntaxhighlight>


===Organizing templates===
<translate><!--T:222--> If <tvar name=1><code>template:d</code></tvar> is modified to recurse into <tvar name=2><code>template:d/2</code></tvar> and <tvar name=3><code>template:d/2</code></tvar> is an ''identical manual copy'' of <tvar name=4><code>template:d</code></tvar> this idiom works fine as the self-recursion safeguard operates dynamically and not statically.</translate>
For templates to be effective, users need to find them, and find out how to use them.  


<translate><!--T:223--> A feasible way for the MediaWiki software to loosen the self-recursion rule would be to require that each recursive call have a distinct argument count from all previous active calls, at most once recursing with the argument count non-decreasing.</translate>
<translate><!--T:224--> That would provide a strong guarantee against infinite self-recursion while enabling useful idioms such as the one described here in a flexible manner.</translate>
<translate><!--T:225--> If the processing path is of low complexity, a simple solution using only one template is to handle each calling convention on a separate if/else branch, duplicating the logic of the processing path within each case.</translate>
<translate><!--T:226--> If the processing path is more complex, each call-structure case can delegate to an implementation template with a unified call structure which provides the final template behaviour.</translate>
<translate>
=== Tables in parameters === <!--T:227-->
<!--T:240-->
Since the pipe character (<tvar name=1><code>|</code></tvar>) and equality sign (<tvar name=2><code>=</code></tvar>) have different meanings in template calls and wikitables, in order to use table markup in the value of a template parameter one generally needs to "escape" those characters (i.e., protect them from interpretation as template markup) using special sequences:
</translate>
* <translate><!--T:255--> the built-in {{<tvar name=1>ll|Help:Magic words</tvar>|magic word}} <tvar name="2"><code><nowiki>{{!}}</nowiki></code></tvar> provides an "escaped" version of <tvar name="3"><code>|</code></tvar> since MediaWiki 1.24</translate>
* <translate><!--T:242--> the built-in magic word <tvar name="1"><code><nowiki>{{=}}</nowiki></code></tvar> provides an "escaped" version of <tvar name="2"><code>=</code></tvar> since MediaWiki 1.39</translate>
<translate><!--T:251--> Before the introduction of these magic words, many wikis used templates to accomplish the same things.</translate>
<translate><!--T:252--> On such a wiki, the magic words take precendence over the same-named templates.</translate>
<translate>
====Example table==== <!--T:243-->
</translate>
{| class=wikitable
!A!!B!!C
|-
|A1||B1||C1
|-
|A2||B2||C1
|}
'''<translate><!--T:244--> Table code:</translate>'''
<syntaxhighlight lang=wikitext>
{| class=wikitable
!A!!B!!C
|-
|A1||B1||C1
|-
|A2||B2||C1
|}
</syntaxhighlight>
'''<translate><!--T:245--> Escaped table code:</translate>'''
<syntaxhighlight lang=wikitext>
{{{!}} class{{=}}wikitable
!A!!B!!C
{{!}}-
{{!}}A1{{!}}{{!}}B1{{!}}{{!}}C1
{{!}}-
{{!}}A2{{!}}{{!}}B2{{!}}{{!}}C2
{{!}}}
</syntaxhighlight>
<translate><!--T:246--> Note that the first left-brace (<tvar name="1"><code>{</code></tvar>) is interpreted as a literal left-brace character because it is immediately followed by the <tvar name="2"><code><nowiki>{{!}}</nowiki></code></tvar> magic word.</translate>
<translate><!--T:247--> Similarly, the last right-brace (<tvar name="1"><code>}</code></tvar>) is interpreted as a literal right-brace character because it is immediately preceeded by the same magic word.</translate>
<translate><!--T:248--> However, in some cases these brace characters do cause problems, so some wikis provide templates for escaping these characters, as well:</translate>
* <translate><!--T:249--> the template call <tvar name="1"><code><nowiki>{{(}}</nowiki></code></tvar> might provide an "escaped" version of <tvar name="2"><code>{</code></tvar></translate>
* <translate><!--T:250--> the template call <tvar name="1"><code><nowiki>{{)}}</nowiki></code></tvar> might provide an "escaped" version of <tvar name="2"><code>}</code></tvar></translate>
<translate><!--T:253--> Some wikis go even further and provide other convenience templates like <tvar name="1">{{Template|(!}} (<code>{|</code>), {{Template|!)}} (<code>|}</code>), {{Template|!!}} (<code>||</code>)</tvar>.</translate>
<translate><!--T:254--> On such a wiki, the code can be simplified a bit to this form:</translate>
<syntaxhighlight lang=wikitext>
{{(!}} class{{=}}wikitable
!A!!B!!C
{{!}}-
{{!}}A1{{!!}}B1{{!!}}C1
{{!}}-
{{!}}A2{{!!}}B2{{!!}}C2
{{!)}}
</syntaxhighlight>
<translate>
== Controlling template inclusion == <!--T:65-->
<!--T:66-->
By default, a template's content is displayed in its entirety, both when viewed directly and when included in another page.</translate>
<translate><!--T:320--> The template's page when viewed directly appears exactly as the template would render without any parameters.</translate>
<translate><!--T:321--> If the template requires parameters to function properly, this will result in raw wikitext syntax or errors as a result of them being missing.</translate>
<translate>
<!--T:326-->
For example:
</translate>
* <translate><!--T:327--> If a parameter has no default value, it shows as the literal text <tvar name="1"><nowiki>{{{1}}}</nowiki></tvar>, indicating the template needs a parameter.</translate>
* <translate><!--T:328--> If a parameter has an empty default value (it is written as <tvar name="1"><nowiki>{{{1|}}}</nowiki></tvar>), it displays nothing, which achieves the intended effect but lacks clarity for self-documentation.</translate> {{tmpl|0=<translate><!--T:329--> Using a non-empty default value like <tvar name=1><code><nowiki>{{{1|</nowiki>$1<nowiki>}}}</nowiki></code></tvar> could clarify a parameter's role, especially for templates involving images.</translate>|<translate><!--T:330--> image</translate>}}
* <translate><!--T:331--> If a parameter without a default is passed to the <tvar name="1"><code>#expr</code></tvar> parser function, it results in an error message: "Expression error: unrecognized punctuation character '{'."</translate>
* <translate><!--T:332--> If a template creates a table, it's helpful for the template page to show the table's structure rather than the wikitext used to make it.</translate> <translate><!--T:333--> To do this, the table syntax isn't enclosed in tags, and each table element includes both <tvar name="1">{{tag|noinclude}}</tvar> and <tvar name="2">{{tag|includeonly}}</tvar> parts where needed.</translate>
<translate>
<!--T:322-->
However, you can control which parts of a template will be seen and included by the use of the <tvar name=noinclude>{{tag|noinclude|open}}</tvar>, <tvar name=includeonly>{{tag|includeonly|open}}</tvar> and <tvar name=onlyinclude>{{tag|onlyinclude|open}}</tvar> tags.
<!--T:67-->
Anything between <tvar name=noinclude_start>{{tag|noinclude|open}}</tvar> and <tvar name=noinclude_end>{{tag|noinclude|close}}</tvar> will be seen only when the template's page is being viewed directly, but not when it is included in another page. This is useful when you want to include text or code in a template that you do not want to propagate to any pages which include it, such as:
<!--T:68-->
* [[<tvar name=1>Special:MyLanguage/Help:Categories</tvar>|Category]] links when categorizing the template itself</translate>
<translate>
<!--T:69-->
* [[<tvar name=1>Special:MyLanguage/Help:Links#Interlanguage links</tvar>|interlanguage links]] to similar templates in other languages</translate>
<translate>
<!--T:70-->
* Explanatory text about how to use the template.</translate> <translate><!--T:334--> It's a common pattern on some wikis to use a template like <tvar name="1">{{tl|documentation}}</tvar> to transclude the documentation from a subpage of the template.</translate> <translate><!--T:335--> For example, <tvar name="1">[[Template:Void]]</tvar> is documented at <tvar name="2">[[Template:Void/doc]]</tvar>.</translate>
<translate>
<!--T:71-->
Likewise, anything between <tvar name=includeonly_start>{{tag|includeonly|open}}</tvar> and <tvar name=includeonly_end>{{tag|includeonly|close}}</tvar> will be processed and displayed only when the page is being included, but not when the template page is being viewed directly, and is useful in situations such as:
<!--T:72-->
* [[<tvar name=1>Special:MyLanguage/Help:Categories</tvar>|Categorizing]] pages which include the template. '''Note:''' when changing the categories applied by a template in this fashion, the categorization of the pages which include that template may not be updated until some time later: this is handled by the {{<tvar name=2>ll|Manual:Job queue</tvar>|job queue}}. To force the re-categorization of a particular page, open that page for editing and save it without changes.</translate>
<translate>
<!--T:73-->
* Ensuring that the template's code is not executed when viewing the template page itself. Typically this is because it expects parameters, and its execution without parameters has an undesired result.
</translate>
<translate><!--T:74--> Everything outside <tvar name=noinclude>{{tag|noinclude|open}}</tvar> and <tvar name=includeonly>{{tag|includeonly|open}}</tvar> is processed and displayed normally; that is, both when the template page is being viewed directly and when the template is included in another page.</translate>
<translate><!--T:127--> The focus is on what is inside these two tags.</translate>
<translate><!--T:128--> Everything outside <tvar name=onlyinclude>{{tag|onlyinclude|open}}</tvar> tags is discarded in the transclusion.</translate>
<translate><!--T:129--> Even sections tagged includeonly are discarded in the transclusion unless they are also tagged as onlyinclude.</translate>
<translate><!--T:130--> The focus is only on what is inside this tag.</translate>
For example, if a page like [[Help:Templates/onlyinclude demo]] has the wikitext:
<syntaxhighlight lang="wikitext">
abc<onlyinclude>def</onlyinclude>ghi<includeonly>jkl</includeonly>
</syntaxhighlight>
The result of transcluding it is {{Help:Templates/onlyinclude demo}}.
<translate>
<!--T:150-->
Nesting of these tags is also possible.
</translate>
<translate><!--T:131--> The three partial transclusion tags enable all possible combinations of what is processed and rendered.</translate>
<translate><!--T:132--> Comments also fill a role.</translate>
<translate><!--T:323--> Inclusion tags are respected when using <tvar name="1"><code><nowiki>{{subst:templatename}}</nowiki></code></tvar>, but they are '''not''' respected when using <tvar name="2"><code><nowiki>{{msgnw:templatename}}</nowiki></code></tvar> as that displays the raw wikitext without any processing.</translate>
== Section transclusion ==
To transclude different sections of a template on different pages, you can wrap the content in onlyinclude tags and use an if statement on parameters to select which section.
Consider "Template:Example" with this wikitext:
<syntaxhighlight lang="wikitext">
== Section 1 ==
{{#ifeq:{{{1|1}}}|1|
Content of section one.
}}
{{#ifeq:{{{1|2}}}|2|
== Section 2 ==
Content of section two.
}}
</syntaxhighlight>
This will render both sections on the example page itself, and allow other pages to transclude the first section with <code><nowiki>{{example|1}}</nowiki></code> and the second section with <code><nowiki>{{example|2}}</nowiki></code>.
Another approach is to use literal parameter syntax instead:
<syntaxhighlight lang="wikitext">
{{{section1|
== Section 1 ==
Content of section one.
}}}
{{{section2|
== Section 2 ==
Content of section two.
}}}
</syntaxhighlight>
Transclude the first section with <code><nowiki>{{example|section2=}}</nowiki></code> and the second section with <code><nowiki>{{example|section1=}}</nowiki></code>. If neither parameter is used, then both sections will display.
A third approach is to use [[mw:Extension:Labeled Section Transclusion|Labeled Section Transclusion]].
<translate>
== Organizing templates == <!--T:75-->
<!--T:76-->
For templates to be effective, users need to find them, and find out how to use them.
<!--T:77-->
To find them, users can:
To find them, users can:
# Click '''Special Pages > All Pages'''
# Click '''<tvar name=special>{{int|specialpages}}</tvar>''' > '''<tvar name=all>{{int|allpages}}</tvar>'''
# In the '''Namespace''' list, choose '''Template''' and click '''Go'''.
# In the '''<tvar name=ns>{{int|namespace}}</tvar>''' list, choose '''Template''' and click '''<tvar name=submit>{{int|allpagessubmit}}</tvar>'''.


<!--T:78-->
To give usage information, include an example like this one on the template page:
To give usage information, include an example like this one on the template page:


<!--T:79-->
<pre><nowiki>
<pre><nowiki>
<noinclude>
<noinclude>
Line 154: Line 730:
</nowiki></pre>
</nowiki></pre>


<!--T:80-->
Then, an editor can simply copy and paste the example to use the template.
Then, an editor can simply copy and paste the example to use the template.
</translate>
<translate><!--T:241--> While editing a page, a list of all templates used is available under the editing form, in a collapsible section titled "<tvar name=1>{{int|templatesused}}</tvar>" (also named "<tvar name=2>{{int|templatesusedpreview}}</tvar>", or "<tvar name=3>{{int|templatesusedsection}}</tvar>" depending on the context).</translate>
<translate><!--T:256--> This list provides a convenient link to the template's page, as well as information about its protection status.</translate>
<translate><!--T:257--> Redirected templates are shown in italics, with the redirect target added as a separate list item.</translate>
<translate>
== Linking to a template == <!--T:133-->
<!--T:158-->
A template page can be linked to like any other wiki page. For example, the link <tvar name=navbarlink>[[Template:Navbar]]</tvar> is generated using the wikicode <tvar name=navbarcode><code><nowiki>[[Template:Navbar]]</nowiki></code></tvar>.
<!--T:159-->
On many wikis, <tvar name=1>[[Template:Tl]]</tvar> can be used to provide a link to a template formatted in a way that shows the "double curly-braces" wikicode necessary to transclude the template without actually doing the tranclusion. For example, the code <tvar name=2><code><nowiki>{{tl|Navbar}}</nowiki></code></tvar> may be used to create the link <tvar name=3>{{tl|Navbar}}</tvar>.
</translate>
<translate><!--T:160--> This construct is commonly used when referring to templates in template documentation, on help pages, and on talk pages.</translate>
<translate><!--T:186--> The same effect can be achieved by using <tvar name=1><code><nowiki>{{[[Template:Navbar|Navbar]]}}</nowiki></code></tvar>, but the <tvar name=2><code>{{tl|tl}}</code></tvar> approach involves much less typing.</translate>
<translate><!--T:187--> On any given wiki the Tl template, if it exists, may or may not render the text in a "code" element or as monospace type.</translate>
<translate><!--T:188--> If not (as on this wiki), another similarly named template may do so.</translate>
<translate><!--T:189--> See, for example, the [[<tvar name=1>Template:Tl#See also</tvar>|"See also" section of our Template:Tl documentation]].</translate>
== Template naming ==
The name of a template is case-sensitive excluding the first character.
You make [[Help:Redirect|redirects]] for alternate capitalizations.
For example, if a template is named "AdminAbbr", you can create a redirect named "Adminabbr".
This way, the template can be called with either <code><nowiki>{{AdminAbbr}}</nowiki></code> or <code><nowiki>{{adminabbr}}</nowiki></code>.
If an editor prefers a mix of upper and lower case for clarity, they can use functions like [[Help:Parser_function#LC|lc]] or [[Help:Parser_function#UC|uc]].
For instance, instead of <code><nowiki>{{CURRENTINTERNETTIME}}</nowiki></code>, they could use <code><nowiki>{{ {{uc:CurrentInternetTime}} }}</nowiki></code>
Because template names are interpreted in the same way to the names of other pages, underscores are replaced with spaces, and any text after a number sign (what would be a [[Help:Links#Anchors|anchor]] in a standard link) is ignored.
An underscore <code>_</code> can be alternative to a blank space.
== Possible uses of templates ==
Templates can be used for any situation in which one wants two or more pages to contain identical or similar content that is edited together rather than independently. They can be used to:
* Provide structured elements on many pages, like [[w:WP:Infoboxes|infoboxes]], [[w:WP:Template index|maintenance templates]], [[w:Template:navbox|navigational boxes]], etc.
* Perform calculations used as a programming tool on various pages, like [[w:Template:Sum]].
* {{anchor|Composite pages}} Build composite pages that display the content of multiple existing pages together, like [[w:WP:Village pump (all)]] which includes content from each section of the village pump. The content of these pages can either be shown individually, or together, but the revision history, watchlist, etc. will only pick up changes to the transcluded pages and the raw wikitext of the composite page itself, not implicit changes to the composite page.
* Share some content between a few related pages. For example, the list at [[Help:Preferences#Beta features]] is duplicated at [[Beta Features#Current Beta Features]]. While on MediaWiki.org that is built using [[Extension:LabeledSectionTransclusion]] instead, it could have been done using a template.
* Store content referenced multiple times on the same page, so it only has to be written and calculated once. For example [[w:Template:Cite Monumentenregister/URL]] is called twice by [[w:Template:Cite Monumentenregister]] in two different places, and using another template means the URL pattern only has to be written once in the base template.
* Use templates as a programming element to generate a loop: if Template:A calls Template:B 10 times with different parameters, then that crudely simulates a for loop. If Template:B calls Template:C 10 times, then you have a nested loop of 100 calls of Template:C. But keep in mind that it is easy to run into the [[Manual:Template limits|template limits]] when using templates as advanced programming constructs, and using [[mw:Extension:Scribunto|Scribunto]] is generally clearer and easier to follow.
<translate>
== Copying from one wiki to another == <!--T:81-->
</translate>
It is possible, if {{ll|Manual:$wgEnableScaryTranscluding|allowed by the wiki configuration}} to transclude templates from other wikis.
This configuration setting is disabled on Wikimedia wikis. Otherwise, you need to manually copy the template and its dependencies from the source wiki to the destination wiki to use it.


==Copying from one wiki to another==
<translate>
Templates often require [http://meta.wikimedia.org/wiki/Help:CSS CSS] or other templates, so users frequently have trouble copying templates from one wiki to another. The steps below should work for most templates.
<!--T:82-->
Templates often require [[<tvar name=1>Special:MyLanguage/Manual:Interface/Stylesheets</tvar>|CSS]] or other templates, so users frequently have trouble copying templates from one wiki to another. The steps below should work for most templates.


=== MediaWiki code ===
=== MediaWiki code === <!--T:83-->
If you have import rights on the new wiki:
 
# Go to [[Special:Export]] on the original wiki, and download an .xml file with the complete history of all necessary templates, as follows:
<!--T:84-->
#* Enter the name of the template in the big text box.
If you have import rights (specifically importupload) on the new wiki:
#* Check the box "Include templates".
 
#* '''Uncheck''' the box "Include only the current revision".
<!--T:85-->
#* Click Export.
# Go to <tvar name=export>[[Special:Export]]</tvar> on the original wiki, and download an .xml file with the complete history of all necessary templates, as follows:</translate>
<translate>
<!--T:86-->
#* Enter the name of the template in the big text box, e.g. "Template:Welcome". Pay special attention to capitalization and special characters — if the template name isn't exactly correct, the export may still occur but the .xml file will not have the expected data.</translate>
<translate>
<!--T:87-->
#* Select the box "<tvar name=export>{{int|export-templates}}</tvar>".</translate>
<translate>
<!--T:88-->
#* Select the box "<tvar name=export2>{{int|exportcuronly}}</tvar>".</translate>
<translate>
<!--T:89-->
#* Click "<tvar name=1>{{int|export-submit}}</tvar>".</translate>
<translate>
<!--T:90-->
# Go to [[Special:Import]] on the new wiki and upload the .xml file.
# Go to [[Special:Import]] on the new wiki and upload the .xml file.


<!--T:91-->
If you don't have import rights on the new wiki:
If you don't have import rights on the new wiki:
# Go to [[Special:Export]] on the original wiki, and download an .xml file with the latest version only of all necessary templates, as follows:
#* Enter the name of the template in the big text box.
#* Check the box "Include templates".
#* '''Check''' the box "Include only the current revision".
#* Click Export.
# Open the file in a text editor and manually copy the text inside the <code><nowiki><text></nowiki></code> tag of each listed template into a similarly named template in your wiki. In the edit summary of each template, link to the original page for attribution.


This will copy the entire code necessary, and will suffice for some templates.
<!--T:114-->
# Go to the template you want to copy from the original wiki. Go to the edit page, and copy all the wikitext</translate>
<translate>
<!--T:258-->
# On the new wiki, go to the page with the same name as the template you copied. Hit create/edit and paste the wikitext you copied. In the edit summary of each template, link to the original page for attribution.</translate>
<translate>
<!--T:259-->
# Back in the original wiki at the edit window, below the edit box, look at the list of "Templates used on this page". For each template listed follow these instructions. Also do that for any template used by any of these templates, and so on.
</translate>
 
<translate><!--T:115--> This will copy the entire code necessary, and will suffice for some templates.</translate>
<translate><!--T:193--> Note that only page elements parsed in rendering the page get exported, consequently documentation subpages are not exported as part of this process.</translate>
<translate><!--T:117--> If it doesn't work also check for red links listed under "Pages transcluded onto the current version of this page:", below the edit box. If there are any repeat the above steps for these as well and also copy the code in the modules.</translate>
 
<translate>
<!--T:118-->
After successfully importing the template and all its linked templates from the other wiki, edit it to change customisations to suit your wiki. For example to change a logo, remove redundant categories or red links.
 
=== Extensions === <!--T:100-->
</translate>
<translate><!--T:101--> An extension often used in templates is ParserFunctions.</translate>
<translate><!--T:164--> Visit page <tvar name=1>{{ll|Help:Extension:ParserFunctions|nsp=0}}</tvar> and check if any of the functions listed there are used in the templates you've copied.</translate>
<translate><!--T:165--> If so, you have to install the <tvar name=1>{{ll|Extension:ParserFunctions|nsp=0}}</tvar> extension.</translate>
<translate><!--T:166--> To install it, you'll need system admin access to the server of your MediaWiki installation.</translate>
 
<translate><!--T:102--> Another dependency that may be used in templates, especially those on Wikipedia, is [[w:Lua (programming language)|Lua]]. Having <tvar name=invoke>'''<code><nowiki>{{#invoke: }}</nowiki></code>'''</tvar> in template code is a good sign for it.</translate>
<translate><!--T:167--> In case it's used, you need to install the <tvar name=1>{{ll|Extension:Scribunto|nsp=0}}</tvar> extension and system admin access is required too.</translate>
<translate><!--T:168--> See that page for more instructions about installing and using the extension.</translate>
 
<translate>
=== CSS and JavaScript code === <!--T:103-->
 
<!--T:104-->
Besides MediaWiki code, many templates make use of CSS and some rely on JavaScript to work fully. If the copied templates are not behaving as expected, this may be the cause. To copy the required CSS and JavaScript to your wiki you'll normally need to have admin privileges, because you'll be editing system messages in the "MediaWiki:" namespace.
 
<!--T:105-->
# Look for the use of CSS classes (text like <code>class="foobar"</code>) in the template text. If those classes appear in "MediaWiki:Common.css" or "MediaWiki:Monobook.css" on the original wiki, copy those classes to "MediaWiki:Common.css" on the new wiki and check if the template is now fine.</translate>
<translate>
<!--T:106-->
# If the copied template is still not working as expected, check if there is code in "MediaWiki:Common.js" or "MediaWiki:Monobook.js" on the original wiki. If so, you can try copying it to "MediaWiki:Common.js" on the new wiki. Normally, it is a good idea to only copy code from trusted sources, and browse the code to identify and select the relevant parts. You may find comments that can serve as clues to identify the functionality of each part.
 
== Redirection == <!--T:324-->
</translate>
If a page uses a [[Help:Redirect|redirect]] as a template, the redirect is resolved before processing the template and the target is used instead. This won't work if the target doesn't exist (a broken redirect), or is itself a redirect (a double redirect).
 
A page that just includes another page as a template might look like a redirect, but there are several differences between them:
 
* The header of the result displays the title of the page it came from.
* No "Redirected from" message is shown.
* Buttons like edit, watch, talk, history, "what links here," and "last modified" point to the referring page. To access the target page, use a section edit link and navigate from there.
* Unless '''includeonly''' and/or '''noinclude tags''' are used, the referring page shares the same categories as the target page.
* "Double redirects" work when one or both are this type of pseudo-redirect.
 
{{Note|type=reminder|text=Embedding works on pages that support [[Help:Redirects|redirects]] and doesn't work on pages without it.}}
 
== Parser functions ==
{{main|Help:Parser functions}}
 
MediaWiki also supports [[Help:Parser functions|parser functions]], which function similarly to templates but follow slightly different syntax:
 
* Parser functions utilize a ":" instead of the initial "|".
* An edit page does not display parser functions used on that page.
* There is no "What links here" feature for parser functions to identify the pages where they are utilized.
* Parser functions templates do not generally accept named parameters, so equal signs generally have no special significance. For example:
: <code><nowiki>{{ #if: not blank | x=abc }}</nowiki></code> gives <code>x=abc</code>
 
<translate>
== See also == <!--T:107-->
 
=== General template usage === <!--T:209-->
</translate>
* [[Manual:Expr parser function syntax]]
* [[Help:Substitution]]
* [[w:Help:Template|w:Help:Template]]
* {{ll|Manual:Advanced templates}} – <translate><!--T:112--> describes even more advanced techniques such as dynamic template calls and variable parameter names</translate>
* {{ll|Help:Multiple-instance templates}} - on the use of multiple instances of the same template on a page.
* [[Manual:Newlines and spaces#Automatic newline]]


=== Extensions ===
<translate>
An extension often used in templates is ParserFunctions. Visit page {{mediawiki|Help:Extension:ParserFunctions|ParserFunctions}} and check if any of the functions listed there are used in the templates you've copied. If so, you have to install the {{mediawiki|Extension:ParserFunctions|ParserFunctions extension}}. To install it, you'll need system admin access to the server of your MediaWiki instalation.
=== Special constructs used in templates === <!--T:210-->
</translate>
* {{ll|Help:Magic words}} – <translate><!--T:109--> fancy stuff you may find in some templates</translate>
* {{ll|Help:Extension:ParserFunctions}} – <translate><!--T:147--> additional fancy control functions such as <tvar name=if>#if</tvar> and <tvar name=switch>#switch</tvar></translate>
* {{ll|Help:Parser functions in templates}} – <translate><!--T:148--> guidance on using parser functions in templates</translate>
* {{ll|Help:TemplateData}}
* {{ll|Help:Extension:ParserFunctions}}
* {{ll|Extension:Scribunto}}


=== CSS and JavaScript code ===
<translate>
Besides MediaWiki code, many templates make use of CSS and some rely on JavaScript to work fully. If the copied templates are not behaving as expected, this may be the cause. To copy the required CSS and JavaScript to your wiki you'll normally need to have admin priviledges, because you'll be editing system messages in the "MediaWiki:" namespace.
=== Other relevant information === <!--T:211-->
</translate>
* {{ll|Help:ExpandTemplates}}
* {{ll|Help:External searches}} – <translate><!--T:108--> a template special use case example</translate>
* {{ll|Manual:Importing Wikipedia infoboxes tutorial}}
* {{ll|Extension:PageTemplates}}
* {{ll|Manual:Creating pages with preloaded text}} – <translate><!--T:212--> Using templates as the starting text of a page</translate>
* {{ll|Help:Transclusion}} – <translate><!--T:113--> embedding pages from [[<tvar name=ns>Special:MyLanguage/Help:Namespaces</tvar>|namespaces]] other than <code>Template:</code></translate>
* {{ll|Manual:Template limits}}
* {{ll|Help:What links here}}
* [[Special:Mostlinkedtemplates]] - shows the templates with the most uses
* [[Special:Unusedtemplates]] - shows templates with no uses (although they may be substituted)
* {{ll|Manual:$wgEnableScaryTranscluding}} - using templates from other wikis
* [[w:WP:Anatomy of a template]]
* [[w:Wikipedia:Transclusion costs and benefits]]
* [[Manual:Parser.php]]
* {{ll|Help:Extension:TemplateSandbox}} - for previewing your changes to a template as it renders elsewhere


# Look for the use of CSS classes (text like <code>class="foobar"</code>) in the template text. If those classes appear in "MediaWiki:Common.css" or "MediaWiki:Monobook.css" on the original wiki, copy them to "MediaWiki:Common.css" on the new wiki and check if the template is now fine.
<translate>
# If the copied template is still not working as expected, check if there is code in "MediaWiki:Common.js" or "MediaWiki:Monobook.js" on the original wiki. If so, you can try copying it to "MediaWiki:Common.js" on the new wiki. Normally, it is a good idea to only copy code from trusted sources, and first browsing the code to identify and select the parts that seem relevant. You may find comments that can serve as clues to identify the functionality of each part. When in doubt, copy all the code to the new wiki.
== External links == <!--T:161-->
</translate>
* [https://dev.miraheze.org/wiki/Miraheze_Developers_Wiki <translate><!--T:162--> Miraheze template repository</translate>] - <translate><!--T:163--> MediaWiki templates intended for general use.</translate>


==See also==
{{help}}
*[[Help:External searches]] – a template special use case example
*[[Help:Magic words]] – fancy stuff you may find in some templates
*[[Help:Parser functions in templates]]
*{{meta|Help:Template}} – contains a much more thorough manual on how exactly templates function
*{{meta|Help:Embed page}} – embedding pages from [[Help:namespaces|namespaces]] other than <code>Template:</code>.


[[Category:Help|{{PAGENAME}}]]
[[Category:Help{{#translation:}}|Templates]]
[[Category:Template]]
[[Category:Template{{#translation:}}]]
{{Languages|Help:Templates}}
[[Category:MediaWiki for site admins{{#translation:}}]]

Latest revision as of 03:18, 27 November 2024

<languages/>

PD {{{text}}}|Important note: When you edit this page, you agree to release your contribution into the public domain. If you don't want this or can't do this because of license restrictions, please don't edit. This page is one of the {{ #ifeq: 
 dankwiki
MediaWiki Public Domain Help Pages Public Domain Help Pages

}}, which can be freely copied into fresh wiki installations and/or distributed with MediaWiki software; see Help:Contents for an overview of all pages. See {{ #ifeq: 

 dankwiki
MediaWiki Project:PD help/Copying Project:PD help/Copying

}} for instructions.}}

PD

<translate> If you have standard texts you want to include on several pages, the MediaWiki template feature comes into play.</translate> <translate> Unlike {{<tvar name=1>ll|Manual:Extensions</tvar>|extensions}} and {{<tvar name=2>ll|Help:Images</tvar>|media files}}, there is no central repository for templates.</translate> <translate> Templates can be newly written or, to save duplicating work already done, exported from another wiki e.g. Wikipedia, and then imported into the target wiki.</translate>

<translate>

Basic usage

Templates are standard wiki pages whose content is designed to be [[<tvar name=1>Special:MyLanguage/Transclusion</tvar>|transcluded]] (embedded) inside other pages. Templates follow a convention that the name is prefixed with "<tvar name=4>Template:</tvar>", assigning it to that [[<tvar name=2>Special:MyLanguage/Help:Namespaces</tvar>|namespace]]; besides this, you can [[<tvar name=3>Special:MyLanguage/Help:Starting a new page</tvar>|create them like any other wiki page]].

To transclude a template, you used double open & close curly brackets {{<tvar name=1>tmpl|0={{$1}}</tvar>|template name}}.

The simplest use of templates is as follows: Create a page called <tvar name=1>Template:Welcome</tvar> with the content below: </translate> 

<translate> Hello! Welcome to the wiki.</translate>

<translate> You have created your first template! Now, insert the code below in a new page: </translate> 

{{Welcome}}

<translate> When the new page is viewed, the text "Hello! Welcome to the wiki." will appear instead of <tvar name=1>{{Welcome}}</tvar>. The template content is transcluded into the other page, i.e., it is integrated in the page.

You can then insert <tvar name=1>{{Welcome}}</tvar> at any point of any page where you wish to welcome someone. Suppose it is used in 100 pages. If you then change the template contents to: </translate> 

<translate> Hi there! Welcome to this wonderful wiki.</translate>

<translate> And revisit any of the 100 pages where the template was used, you'll see the new text instead of the original one. In this way, you have changed the content of 100 pages without editing them, because the template is transcluded into these pages.

This is the basic mechanism. There are several additional features of transclusion that enrich this mechanism and make templates very useful. </translate>

{{#if:Usage|{{#if:|{{#if:|{{#if:|{{#if:|{{#if:|{{#if:|{{#if:|{{#if:|{{#if:|{{#if: 

   |Template:Anchor (or Anchors): too many anchors, maximum is ten}}}} }} }} }} }} }} }} }} }} }}

<translate>

Ways to invoke a template

Templates can be used in other pages in these ways:

  • {{Name}} — As described above, this text (commonly referred to as a "template call") will be dynamically replaced by the content of the page titled Template:Name (a process called "transclusion") every time the page with the template call is loaded (i.e., viewed by a reader of the wiki).</translate> <translate> Because the template call remains in the pages's source, any subsequent change to Template:Name will be seen on the page containing the template call.</translate> <translate> Also, the page will be listed among those that "link to" the template.</translate>

<translate>

  • {{subst:Name}} — When this type of template call is used, it will be replaced by a static copy of the content of Template:Name as of the time the page containing the template call is saved.</translate> <translate> That is, a copy of the contents of Template:Name will be substituted for the template call.</translate> <translate> No link is maintained between the page and the template, so each can be edited further without affecting the other.</translate> <translate> In effect, there is little difference between substituting the content in this way and simply typing it into the page's source "manually".</translate> <translate> See <tvar name=1>{{#ifeq:Help:Substitution|
 |

}}[[Special:MyLanguage/Help:Substitution|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Help|Help:}}Substitution/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 12!=0
   |{{#ifeq:en|en
     |Substitution
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Help:Substitution
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Substitution
     |Substitution
     |Help:Substitution
   }}
   |Help:Substitution
 }}

}}}}]]{{#ifeq:Help:Substitution| 

 |

}} </tvar> for more information.</translate> <translate>

  • {{safesubst:Name}} — This was introduced to allow for recursive substitution in cases where templates contain calls to other templates or parser functions.</translate> <translate> See <tvar name=1>{{#ifeq:Help:Substitution|
 |

}}[[Special:MyLanguage/Help:Substitution|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Help|Help:}}Substitution/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 12!=0
   |{{#ifeq:en|en
     |Substitution
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Help:Substitution
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Substitution
     |Substitution
     |Help:Substitution
   }}
   |Help:Substitution
 }}

}}}}]]{{#ifeq:Help:Substitution| 

 |

}} </tvar> for more information.</translate> <translate>

  • {{msgnw:Name}} — This displays the template content as raw wiki syntax (the way <tvar name=1>Template:Tag</tvar> does) when the page containing it is viewed.</translate> <translate> For example, <tvar name="1">{{msgnw:Template:Thankyou}}</tvar> displays:</translate>

{{msgnw:Template:Thankyou/{{#ifexist:Template:Thankyou/en|en|en}}}}

<translate> In fact, an ordinary wiki page can also be used as a template, simply by specifying the namespace it resides in, so:

  • {{Template:Pagename}} transcludes the page titled Template:Pagename (equivalent to {{Pagename}})</translate>

<translate>

  • {{Talk:Pagename}} transcludes the page titled Talk:Pagename</translate>

<translate>

  • {{:Pagename}} transcludes the page titled Pagename (i.e., in the main namespace)</translate>

<translate>

    • {{subst::Pagename}} substitutes the contents of the page titled Pagename

If the specified namespace doesn't exist, the full title is assumed to be a template:

  • <tvar name=1>{{Foo:Bar}}</tvar> transcludes <tvar name=2>Template:Foo:Bar</tvar>

</translate>

<translate> Regardless of what syntax is used, the name of the template can be relative to the current page</translate> Template:Tmpl

<translate> It can also be generated dynamically. </translate> Template:Tmpl

<translate>

Parameters

To enrich the mechanism of transclusion, MediaWiki allows parameters to be passed to a template when it is transcluded. Parameters allow the template to produce different contents or have different behaviors.

Suppose you wish to insert a little thank you note in the [[<tvar name=1>Special:MyLanguage/Help:Talk pages</tvar>|talk page]] of other users, such as:

Example sunflower image
Example sunflower image
A little thank you...
for all your effort.
hugs, Me


The thank you note will have a reason (in this case, "all your effort") and a signature ("Me"). Your objective is for any user to be able to thank any other user, for any reason whatsoever. </translate>

<translate> So that the note will look similar everywhere it is used, you can define a template called <tvar name=tmpl>{{#ifeq:Template:Thankyou| 

 |

}}[[Special:MyLanguage/Template:Thankyou|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Template|Template:}}Thankyou/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 10!=0
   |{{#ifeq:en|en
     |Thankyou
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Template:Thankyou
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Thankyou
     |Thankyou
     |Template:Thankyou
   }}
   |Template:Thankyou
 }}

}}}}]]{{#ifeq:Template:Thankyou| 

 |

}} </tvar>, for example.</translate> <translate> Although the note should look similar whenever a user thanks another user, its specific contents (i.e., the reason and the signature) will be different.</translate> <translate> For that reason, you should pass them as parameters.</translate> <translate> If we ignore the remaining elements to format the box and place the image, the core content of the template will be this:</translate> 

<translate nowrap><!--T:32-->
'''A little thank you...'''
for {{{1}}}.
hugs, {{{2}}}</translate>

<translate> Notice the use of <tvar name=1>{{{1}}}</tvar> and <tvar name=2>{{{2}}}</tvar>. This is the way to identify, within templates, the parameters that will be passed in when the template is used. Note that, within the template, each parameter is surrounded by three braces: <tvar name=braces>{{{ }}}</tvar>. This is different from normal template name usage.

When using the template on a page, you fill in the parameter values, separated by a "pipe" character (<tvar name=pipe>|</tvar>). MediaWiki allows parameters to be passed to the template in three ways: Anonymously, Numbered, and Named.

Anonymous parameters

To pass in anonymous parameters, list the values of those parameters sequentially: </translate> 

<translate> {{Thankyou|all your effort|Me}}</translate>

<translate> In this case, the {{Thankyou}} template receives parameters {{{1}}}=all your effort and {{{2}}}=Me, producing:

Example sunflower image
Example sunflower image
A little thank you...
for all your effort.
hugs, Me


The order in which anonymous parameters are passed in is crucial to its behavior. Reversing the order of the parameters, like so: </translate> 

<translate> {{Thankyou|Me|all your effort}}</translate>

<translate> would produce this result:

Example sunflower image
Example sunflower image
A little thank you...
for Me.
hugs, all your effort

</translate>

{{#if: <translate> Identifying parameters by order (with <tvar name=1>{{{1}}}</tvar>, etc.) works only with anonymous parameters.</translate> <translate> Any parameters identified by name, as shown below, will not be accessible to the template using ordinal numbers.</translate>|

|Note}} Note: {{#if: <translate> Identifying parameters by order (with <tvar name=1>{{{1}}}</tvar>, etc.) works only with anonymous parameters.</translate> <translate> Any parameters identified by name, as shown below, will not be accessible to the template using ordinal numbers.</translate>|<translate> Identifying parameters by order (with <tvar name=1>{{{1}}}</tvar>, etc.) works only with anonymous parameters.</translate> <translate> Any parameters identified by name, as shown below, will not be accessible to the template using ordinal numbers.</translate>

}} {{#if: <translate> If an equal sign appears inside the argument to an anonymous template parameter, that parameter may be misinterpreted as a [[<tvar name=1>#Named parameters</tvar>|named parameter]] (which is explained below in this document) treating the text before the equal sign as the parameter name and the text after it as the argument value.</translate> <translate> This is a common problem when you need to include an external link, or an HTML element with attributes (see <tvar name=1>Template:Task</tvar>).</translate> <translate> The workaround is to use named parameters instead, or even numbered parameters as explained in the following section.</translate>|

|Note}} Note: {{#if: <translate> If an equal sign appears inside the argument to an anonymous template parameter, that parameter may be misinterpreted as a [[<tvar name=1>#Named parameters</tvar>|named parameter]] (which is explained below in this document) treating the text before the equal sign as the parameter name and the text after it as the argument value.</translate> <translate> This is a common problem when you need to include an external link, or an HTML element with attributes (see <tvar name=1>Template:Task</tvar>).</translate> <translate> The workaround is to use named parameters instead, or even numbered parameters as explained in the following section.</translate>|<translate> If an equal sign appears inside the argument to an anonymous template parameter, that parameter may be misinterpreted as a [[<tvar name=1>#Named parameters</tvar>|named parameter]] (which is explained below in this document) treating the text before the equal sign as the parameter name and the text after it as the argument value.</translate> <translate> This is a common problem when you need to include an external link, or an HTML element with attributes (see <tvar name=1>Template:Task</tvar>).</translate> <translate> The workaround is to use named parameters instead, or even numbered parameters as explained in the following section.</translate>

}}

<translate>

Numbered parameters

To pass in parameters by number, identify each parameter when passing it: </translate> 

<translate> {{Thankyou|2=Me|1=your friendship}}</translate>

<translate> This time, template {{Thankyou}} receives parameters {{{1}}}=your friendship and {{{2}}}=Me, though they have been supplied in inverse order, and produces:

Example sunflower image
Example sunflower image
A little thank you...
for your friendship.
hugs, Me

</translate>

{{#if: <translate> This may also be useful when any of the numbered parameters contains an "<tvar name=1>=</tvar>" sign.</translate>|

|Note}} Note: {{#if: <translate> This may also be useful when any of the numbered parameters contains an "<tvar name=1>=</tvar>" sign.</translate>|<translate> This may also be useful when any of the numbered parameters contains an "<tvar name=1>=</tvar>" sign.</translate>

}}

<translate> Examples
</translate>
<translate nowrap><!--T:207--> {{Thankyou|1=adding “=”|2=Me}}</translate>

<translate> produces:</translate>

<translate>

Example sunflower image
Example sunflower image
A little thank you...
for adding “=”.
hugs, Me

</translate>

{{#if: <translate> This also requires numbering each other parameter.</translate>|

}}Warning Warning: {{#if: <translate> This also requires numbering each other parameter.</translate>|<translate> This also requires numbering each other parameter.</translate>

}}

<translate>

Named parameters

The third way of passing parameters is by name instead of numbers. In this case, the template contents would be changed to: 

'''A little thank you...'''
for {{{reason}}}.
hugs, {{{signature}}}

Within the template, we use {{{reason}}} and {{{signature}}} to identify each parameter, instead of a number. To pass these parameters by name, identify each parameter when passing it: </translate> 

<translate> {{Thankyou|signature=Me|reason=being who you are}}</translate>

<translate> In this case, template {{Thankyou}} receives parameters {{{reason}}}=being who you are and {{{signature}}}=Me and produces:

Example sunflower image
Example sunflower image
A little thank you...
for being who you are.
hugs, Me


Named parameters are case-sensitive, so: 

{{Thankyou|signature=Me|Reason=being who you are|reason=being case-sensitive}}

produces:

Example sunflower image
Example sunflower image
A little thank you...
for being case-sensitive.
hugs, Me


The advantage of using named parameters in your template, besides also being flexible in the order parameters can be passed, is that it makes the template code much easier to understand if there are many parameters.

Spaces and newlines are automatically stripped from the start and end of named parameter names and values, but are preserved in unnamed parameters.

Mixing named and unnamed parameters

If the template supports it, both kinds of parameters can be used in one call. </translate>

For example, {{Thankyou|supporting both parameter types|signature=Me}} results in:

Example sunflower image
Example sunflower image
A little thank you...
for supporting both parameter types.
hugs, Me


Be careful when doing this, because it can result in conterintuitive results as unnamed parameter counts are based only on the unnamed parameters, not the named parameters. For example, {{Thankyou|Me|reason=supporting both parameter types}} results in:

Example sunflower image
Example sunflower image
A little thank you...
for supporting both parameter types.
hugs, {{{2}}}


The template is coded to prefer the named parameter for the reason over the unnamed parameter, resulting in the "Me" being lost and no signature being given. This results in a default value of {{{2}}} being shown, as explained below.

<translate>

Default values

</translate> Template:See also <translate> If you transclude a template that expects parameters, but do not provide their arguments, in this way: </translate> 

<translate> {{Thankyou}}</translate>

<translate> in the numbered parameters example above you would get the following: </translate>

Example sunflower image
Example sunflower image
A little thank you...
for {{{1}}}.
hugs, {{{2}}}


<translate> Since no arguments were passed in, the template presents the parameters themselves, instead of their respective values. In these cases, it may be useful to define default values for the parameters, i.e. values that will be used if no value is passed in. For example, if the template contents are changed to: </translate> 

<translate nowrap><!--T:62-->
'''A little thank you...'''
for {{{reason|everything}}}.
hugs, {{{signature|Me}}}</translate>

<translate> then {{{reason|everything}}} defines that if no argument is provided for parameter {{{reason}}}, then the value everything will be used. Similarly, {{{signature|Me}}}, defaults parameter {{{signature}}} to value Me. Now, transcluding the template again without passing any argument results in the following: </translate>

<translate>

Example sunflower image
Example sunflower image
A little thank you...
for everything.
hugs, Me

</translate>

{{#if: <translate> The value of a parameter can be an empty string.</translate> <translate> For example, in <tvar name=1>{{foo|bar=}}</tvar> or <tvar name=2>{{foo|bar=|baz=qux}}</tvar>, the <tvar name=5>foo</tvar> template considers the <tvar name=3>bar</tvar> parameter to be <tvar name=4>""</tvar>.</translate> <translate> This is different from omitting the parameter altogether, which leaves it undefined and triggers the default value mechanism described above.</translate>|

|Note}} Note: {{#if: <translate> The value of a parameter can be an empty string.</translate> <translate> For example, in <tvar name=1>{{foo|bar=}}</tvar> or <tvar name=2>{{foo|bar=|baz=qux}}</tvar>, the <tvar name=5>foo</tvar> template considers the <tvar name=3>bar</tvar> parameter to be <tvar name=4>""</tvar>.</translate> <translate> This is different from omitting the parameter altogether, which leaves it undefined and triggers the default value mechanism described above.</translate>|<translate> The value of a parameter can be an empty string.</translate> <translate> For example, in <tvar name=1>{{foo|bar=}}</tvar> or <tvar name=2>{{foo|bar=|baz=qux}}</tvar>, the <tvar name=5>foo</tvar> template considers the <tvar name=3>bar</tvar> parameter to be <tvar name=4>""</tvar>.</translate> <translate> This is different from omitting the parameter altogether, which leaves it undefined and triggers the default value mechanism described above.</translate>

}} {{#if: If you need to treat an empty string the same way as a missing parameter, you can use a conditional operator through an extension like ParserFunctions. For instance, {{#if:{{{1|}}}|{{{1|}}}|undefined}} returns undefined if the parameter is either undefined or empty, while {{{1|undefined}}} does so only if the parameter is undefined.|

|Note}} Note: {{#if: If you need to treat an empty string the same way as a missing parameter, you can use a conditional operator through an extension like ParserFunctions. For instance, {{#if:{{{1|}}}|{{{1|}}}|undefined}} returns undefined if the parameter is either undefined or empty, while {{{1|undefined}}} does so only if the parameter is undefined.|If you need to treat an empty string the same way as a missing parameter, you can use a conditional operator through an extension like ParserFunctions. For instance, {{#if:{{{1|}}}|{{{1|}}}|undefined}} returns undefined if the parameter is either undefined or empty, while {{{1|undefined}}} does so only if the parameter is undefined.

}}

<translate> Often default values are used to specify alternate names of parameters.</translate> <translate> For example, if you have <tvar name=1>{{{a|{{{b|}}} }}}</tvar>, the template will first look for a parameter named "<tvar name=2>a</tvar>".</translate> <translate> If it is not set, it will use the parameter named "<tvar name=1>b</tvar>".</translate> <translate> If neither "<tvar name=1>a</tvar>" nor "<tvar name=2>b</tvar>" is set, it will output nothing.</translate>

Passing parameters to other templates

If raw parameter syntax is generated by the above template call, and then passed through to another template, it is not interpreted as a parameter. This means that {{thankyou2}}, which just calls {{thankyou}} with no parameters, does not work: Template:Tlx -> Template:Thankyou2.

You instead need to explicitly pass the parameter to the other template, i.e if {{thankyou3}} contains 

{{thankyou|{{{1}}}|{{{2}}}}}}

then Template:Tlx -> Template:Thankyou3 works properly.

This example does not preserve emptiness vs. undefinedness in parameter values - you would need more complicated syntax if you wanted to do that.

<translate>

Empty vs undefined parameters

</translate> <translate> The <tvar name=1>{{t2demo|| a }}</tvar> (refer to <tvar name="2">{{t2demo}}</tvar> ), with a double pipe, sets the first parameter to an empty string instead of leaving it undefined.</translate> <translate> It produces the output <tvar name=1>start--middle- a -end</tvar>, similar to how <tvar name=2>{{t2demo|1=|2= a }}</tvar> results in <tvar name=3>Template:T2demo</tvar>.</translate> <translate> On the other hand, explicitly setting the parameter "2" to "a," results in the first unnamed parameter being left undefined:</translate>

<translate> <tvar name="1">{{t2demo|2= a }}</tvar> results in <tvar name="2">Template:T2demo</tvar>

If the second parameter should not be trimmed, it must be unnamed.

Therefore, you can assign an empty string to the first parameter, but you cannot leave it undefined.

Making emptiness and undefinedness equivalent

Good template coding practices result in passing an empty string to a parameter working the same as not assigning any value. This makes things easier and more consistent.

For example, using <tvar name="1">p=</tvar> can show that a template has a parameter "p" that doesn't have a value yet.

To make an empty string and an undefined value equivalent, use the following approaches: </translate>

  • <translate> Use <tvar name="1">{{{p|}}}</tvar> exclusively instead of <tvar name="2">{{{p}}}</tvar> or <tvar name="3">q</tvar> where "q" is a non-empty value.</translate>
  • <translate> Use conditional checks like <tvar name="1">{{#if:{{{p|}}}|..{{{p}}}..|..}}</tvar>, to ensure <tvar name="2">{{{p}}}</tvar> is only used when it has a value.</translate>

If for some reason you want to treat undefined parameters differently from empty parameters or any other possible value you can compare the same parameter twice with different defaults, i.e {{#ifeq:{{{foo|bar}}}|{{{foo|baz}}}|parameter is defined|parameter is undefined}}. <translate>

Using equals signs in unnamed parameters

</translate> <translate> Unnamed parameters can include equals signs, but this must be done indirectly.</translate> <translate> Here are some methods using <tvar name="1">template:T1demo</tvar>:</translate>

<translate> Default Value for Undefined Parameter</translate>

<translate> Assign a default value to an undefined parameter:</translate> 

{{T1demo|{{{1| a=b }}}}}

<translate> This renders as:</translate> Template:T1demo.

<translate> Using the <tvar name="1">{{=}}</tvar> parser function</translate>

<translate> Use a parser function that safely includes an equals sign:</translate> 

{{T1demo| a{{=}}b }}

<translate> This renders as:</translate> Template:T1demo.

<translate> HTML Entities</translate>

<translate> Replace the equals sign with an HTML entity for display:</translate> 

{{T1demo| a=b }}

<translate> This renders as:</translate> Template:T1demo.

<translate> This renders correctly without affecting the other parameters.

Handling unmatched curly and square brackets

Unmatched curly brackets (<tvar name=1>{{</tvar>, <tvar name="2">}}</tvar>) or square brackets (<tvar name=3>[[</tvar>, <tvar name="4">]]</tvar>) must be inside nowiki tags or use HTML entities: </translate>

  • <translate> Rendering curly brackets have two options:</translate>
    • <translate> Use <tvar name="1"><nowiki>{{</nowiki></tvar> or <tvar name="2">&#123;</tvar> for <tvar name="3">{</tvar></translate>
    • <translate> Use <tvar name="1"><nowiki>}}</nowiki></tvar> or <tvar name="2">&#125;</tvar> for <tvar name="3">}</tvar>.</translate>
  • <translate> Use <tvar name="1">&#91;</tvar> for <tvar name="2">[</tvar> and <tvar name="3">&#93;</tvar> for <tvar name="4">]</tvar>.</translate>

<translate> Below are some examples: </translate>

<translate> Unmatched curly brackets</translate>
{{T1demo| <nowiki>{{</nowiki>content<nowiki>}}</nowiki> }}

<translate> This correctly renders the braces without breaking the template.</translate>

<translate> Unmatched square brackets</translate>
{{T1demo| text [link] more text }}

<translate> This correctly renders the braces without breaking the template.</translate>

<translate> This renders as:</translate> Template:T1demo

<translate> Unmatched pairs not placed in nowiki tags either prevent template expansion or are taken as closing braces for the template call.

Below are some examples: </translate> 

{{T1demo|abc]]def[[ghi}}

<translate> This will not expand correctly because of unmatched brackets.

The correct use: </translate> 

{{T1demo|abc<nowiki>]]</nowiki>def<nowiki>[[</nowiki>ghi}}

<translate> This renders as:</translate> Template:T1demo

Template-generated brackets

An alternate technique for passing arguments with unmatched brackets is to wrap them in another template. In that situation, (which exists with {{((}} and {{))}}) on this wiki), the unmatched brackets will be rendered literally, and not decoded as another template call. For example: 

{{t1demo|{{((}}t1demo{{))}}}}

results in: Template:T1demo

When substituting a template, template inclusions are parsed once when the subst happens (with the same caveats explained above) and then a second time when rendering the resulting wikitext. For example: 

{{subst:((}}t1demo|foo}}

will expand on save to: 

{{((}}t1demo|foo}}

which will then render as: 

Template:T1demo

If the wikitext generated via the first subst itself includes "subst:" syntax it will not be processed on the same save, but may be on the next save. This technique may be used to implement recursive substitutions that take multiple saves to evaluate.

Using pipes in parameter values

A parameter value cannot contain a pipe character (|), because it would be interpreted as the end of that parameter and the start of the next parameter. This can be worked around by using the {{#ifeq:Help:Parser function| 

 |

}}{{#if:parser function |parser function |parser function}}{{#ifeq:Help:Parser function| 

 |

}} {{!}}, or the HTML entity &124;. The two methods of doing this have slightly different behavior, which can be relevant in some corner cases like when a template is producing wikitable syntax.

Example: {{T1demo|abc|def}} produces: Template:T1demo

The "def" doesn't display because it is treated as part of another unnamed parameter, which the template does not use.

{{T1demo|abc{{!}}def}} produces: Template:T1demo

The "def" displays properly.

{{T1demo|abc|def}} produces: Template:T1demo

The "def" displays properly again.

Formatting template calls using extra parameters

Since templates ignore parameters they are passed but do not handle specifically, they can be used as a way of a adding extra whitespace or unused content to the template call.

For example: 

{{template name|foo|bar|baz|mumble|quux}}

is equivalent to, assuming the template doesn't recognize SPACEN as a parameter name: 

{{template name|SPACE1=
|foo|SPACE2=
|bar|SPACE3=Random stuff
|baz|SPACE4=
   |mumble|SPACE5=
  quux
}}

It is also possible to use the same name for each spacer (often the empty string), but this will populate Category:Pages using duplicate arguments in template calls, which many wikis prefer to keep empty to catch instances of user error.

This can be used to make the template render in a way similar to its output, like showing each row of w:Template:Chess position on its own like to make the wikitext also look like a chessboard.

Tracking parameter usage

Template:See also

It may be wise for a template to add a link or category to a page if a certain parameter or combination of parameters is used, to make if possible to easily determine what pages are using a given parameter, and thus what the impacts of changing that parameter in the template would be.

<translate>

Evaluation process

</translate>

{{#if: <translate> This is an advanced topic which you can skip unless you need it.</translate>|

|Note}} Note: {{#if: <translate> This is an advanced topic which you can skip unless you need it.</translate>|<translate> This is an advanced topic which you can skip unless you need it.</translate>

}}

<translate> Generally speaking, template parameters are substituted into the template after tokenization, but as is.</translate> <translate> They are not evaluated until they are used.</translate>

<translate> This has a few consequences:</translate>

  1. <translate> If you have a <tvar name=1>Template:Start</tvar> containing <tvar name=2>{{mytemplate</tvar>, and a <tvar name=3>Template:End</tvar> containing <tvar name=4>|foo=bar}}</tvar>, and put <tvar name=5>{{start}}{{end}}</tvar> on a page, mytemplate isn't transcluded, because tokens like "|" cannot be added by a template and keep their special meaning in templates.</translate> <translate> You can still use templates to control the name of a parameter or template, but you cannot split a template call amongst multiple templates.</translate>
  2. <translate> Dead-code elimination:</translate> <translate> If you make a template call like <tvar name=1>{{foo|{{DISPLAYTITLE:Bar}} }}</tvar>, and Template:Foo does not contain <tvar name=2>{{{1}}}</tvar>, then the <tvar name=3>DISPLAYTITLE</tvar> is not used, since it is only evaluated when needed, and there is no parameter to substitute it into, so it is never evaluated.</translate> <translate> This usually comes into play when using <tvar name=3>{{#ifeq:Extension:ParserFunctions|
 |

}}[[Special:MyLanguage/Extension:ParserFunctions|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:|:}}Extension:ParserFunctions/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 0!=0
   |{{#ifeq:en|en
     |Extension:ParserFunctions
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Extension:ParserFunctions
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Extension:ParserFunctions
     |Extension:ParserFunctions
     |Extension:ParserFunctions
   }}
   |Extension:ParserFunctions
 }}

}}}}]]{{#ifeq:Extension:ParserFunctions| 

 |

}} </tvar>, and can be especially noticed when used in combination with the <tvar name=2>int:</tvar> magic word that varies by user language.</translate> <translate> This isn't perfect, and in some cases even if the result of expanding a template is not used (because it is part of an if statement condition, for example), the process of evaluating it can still have side effects.</translate> <translate> For example, any {{<tvar name=1>ll|Help:Links</tvar>|links}} produced or other templates used will still be added to <tvar name=2>Special:WhatLinksHere</tvar> even if they are not displayed.</translate>


Template parameters are pass by value, which means a template cannot modify its arguments. Parameters are treated as associative array, and parameter names are evaluated before parameter values. If the same parameter name is given more than once (either as named or unnamed), only the last instace is used, and the page is added to Category:Pages using duplicate arguments in template calls.

<translate> Template calls starting with the magic word <tvar name=1>subst:</tvar> or <tvar name=2>safesubst:</tvar> are evaluated in a separate first pass that only happens at save time, along with <tvar name=3>~~~~</tvar> and links using the [[<tvar name=4>Special:MyLanguage/pipe trick</tvar>|pipe trick]].</translate> <translate> If they cannot be evaluated during the first pass, <tvar name=1>subst:</tvar> calls are ignored, and <tvar name=2>safesubst:</tvar> are treated as if a normal template.</translate>

<translate> Many but not all parser functions, parser tags and trancluded special pages are not directly included like templates but instead are replaced by a "strip marker".</translate> <translate> This means you cannot manipulate the results with parser functions like <tvar name=1>padleft:</tvar> or similar functions from extensions, as they see the strip marker instead of the result of the parser function.</translate>

<translate>

Recursion in templates

</translate> <translate> Including a template in itself won't throw MediaWiki into infinite recursion.</translate> <translate> MediaWiki will stop the recursion with the template's name in bold.</translate> <translate> For example, if the content of Template:Aaaa is <tvar name=code>a {{Aaaa}} z</tvar>, it'll display "<tvar name=result>a a Template loop detected: Template:Aaaa z z</tvar>".</translate>

<translate> This safeguard precludes a potentially useful template idiom where a template self-normalizes its own calling arguments.</translate> <translate> In this forbidden example <tvar name=1>template:d</tvar> can either be called <tvar name=2>{{d|20200311}}</tvar> or <tvar name=3>{{d|y=2020|m=3|d=11}}</tvar>.</translate> <translate> If called in the first manner, it recurses into itself with the second argument structure (obtained using string parser functions), which then follows a unified processing path.</translate> 

{{#if:{{{1|}}}|{{d|y={{#sub:{{{1}}}|0|4}}|m={{#sub:{{{1}}}|4|2}}|d={{#sub:{{{1}}}|6|2}}}}|<!-- processing path with arguments y,m,d regardless of original call pattern -->}}

<translate> If <tvar name=1>template:d</tvar> is modified to recurse into <tvar name=2>template:d/2</tvar> and <tvar name=3>template:d/2</tvar> is an identical manual copy of <tvar name=4>template:d</tvar> this idiom works fine as the self-recursion safeguard operates dynamically and not statically.</translate>

<translate> A feasible way for the MediaWiki software to loosen the self-recursion rule would be to require that each recursive call have a distinct argument count from all previous active calls, at most once recursing with the argument count non-decreasing.</translate> <translate> That would provide a strong guarantee against infinite self-recursion while enabling useful idioms such as the one described here in a flexible manner.</translate>

<translate> If the processing path is of low complexity, a simple solution using only one template is to handle each calling convention on a separate if/else branch, duplicating the logic of the processing path within each case.</translate> <translate> If the processing path is more complex, each call-structure case can delegate to an implementation template with a unified call structure which provides the final template behaviour.</translate>

<translate>

Tables in parameters

Since the pipe character (<tvar name=1>|</tvar>) and equality sign (<tvar name=2>=</tvar>) have different meanings in template calls and wikitables, in order to use table markup in the value of a template parameter one generally needs to "escape" those characters (i.e., protect them from interpretation as template markup) using special sequences: </translate>

  • <translate> the built-in {{<tvar name=1>ll|Help:Magic words</tvar>|magic word}} <tvar name="2">{{!}}</tvar> provides an "escaped" version of <tvar name="3">|</tvar> since MediaWiki 1.24</translate>
  • <translate> the built-in magic word <tvar name="1">{{=}}</tvar> provides an "escaped" version of <tvar name="2">=</tvar> since MediaWiki 1.39</translate>

<translate> Before the introduction of these magic words, many wikis used templates to accomplish the same things.</translate> <translate> On such a wiki, the magic words take precendence over the same-named templates.</translate>

<translate>

Example table

</translate>

A B C
A1 B1 C1
A2 B2 C1

<translate> Table code:</translate> 

{| class=wikitable
!A!!B!!C
|-
|A1||B1||C1
|-
|A2||B2||C1
|}

<translate> Escaped table code:</translate> 

{{{!}} class{{=}}wikitable
!A!!B!!C
{{!}}-
{{!}}A1{{!}}{{!}}B1{{!}}{{!}}C1
{{!}}-
{{!}}A2{{!}}{{!}}B2{{!}}{{!}}C2
{{!}}}

<translate> Note that the first left-brace (<tvar name="1">{</tvar>) is interpreted as a literal left-brace character because it is immediately followed by the <tvar name="2">{{!}}</tvar> magic word.</translate> <translate> Similarly, the last right-brace (<tvar name="1">}</tvar>) is interpreted as a literal right-brace character because it is immediately preceeded by the same magic word.</translate> <translate> However, in some cases these brace characters do cause problems, so some wikis provide templates for escaping these characters, as well:</translate>

  • <translate> the template call <tvar name="1">{{(}}</tvar> might provide an "escaped" version of <tvar name="2">{</tvar></translate>
  • <translate> the template call <tvar name="1">{{)}}</tvar> might provide an "escaped" version of <tvar name="2">}</tvar></translate>

<translate> Some wikis go even further and provide other convenience templates like <tvar name="1">Template:Template ({|), Template:Template (|}), Template:Template (||)</tvar>.</translate> <translate> On such a wiki, the code can be simplified a bit to this form:</translate> 

{{(!}} class{{=}}wikitable
!A!!B!!C
{{!}}-
{{!}}A1{{!!}}B1{{!!}}C1
{{!}}-
{{!}}A2{{!!}}B2{{!!}}C2
{{!)}}

<translate>

Controlling template inclusion

By default, a template's content is displayed in its entirety, both when viewed directly and when included in another page.</translate> <translate> The template's page when viewed directly appears exactly as the template would render without any parameters.</translate> <translate> If the template requires parameters to function properly, this will result in raw wikitext syntax or errors as a result of them being missing.</translate> <translate> For example: </translate>

  • <translate> If a parameter has no default value, it shows as the literal text <tvar name="1">{{{1}}}</tvar>, indicating the template needs a parameter.</translate>
  • <translate> If a parameter has an empty default value (it is written as <tvar name="1">{{{1|}}}</tvar>), it displays nothing, which achieves the intended effect but lacks clarity for self-documentation.</translate> Template:Tmpl
  • <translate> If a parameter without a default is passed to the <tvar name="1">#expr</tvar> parser function, it results in an error message: "Expression error: unrecognized punctuation character '{'."</translate>
  • <translate> If a template creates a table, it's helpful for the template page to show the table's structure rather than the wikitext used to make it.</translate> <translate> To do this, the table syntax isn't enclosed in tags, and each table element includes both <tvar name="1">Template:Tag</tvar> and <tvar name="2">Template:Tag</tvar> parts where needed.</translate>

<translate> However, you can control which parts of a template will be seen and included by the use of the <tvar name=noinclude>Template:Tag</tvar>, <tvar name=includeonly>Template:Tag</tvar> and <tvar name=onlyinclude>Template:Tag</tvar> tags.

Anything between <tvar name=noinclude_start>Template:Tag</tvar> and <tvar name=noinclude_end>Template:Tag</tvar> will be seen only when the template's page is being viewed directly, but not when it is included in another page. This is useful when you want to include text or code in a template that you do not want to propagate to any pages which include it, such as:

  • [[<tvar name=1>Special:MyLanguage/Help:Categories</tvar>|Category]] links when categorizing the template itself</translate>

<translate>

  • [[<tvar name=1>Special:MyLanguage/Help:Links#Interlanguage links</tvar>|interlanguage links]] to similar templates in other languages</translate>

<translate>

  • Explanatory text about how to use the template.</translate> <translate> It's a common pattern on some wikis to use a template like <tvar name="1">{{documentation}}</tvar> to transclude the documentation from a subpage of the template.</translate> <translate> For example, <tvar name="1">Template:Void</tvar> is documented at <tvar name="2">Template:Void/doc</tvar>.</translate>

<translate> Likewise, anything between <tvar name=includeonly_start>Template:Tag</tvar> and <tvar name=includeonly_end>Template:Tag</tvar> will be processed and displayed only when the page is being included, but not when the template page is being viewed directly, and is useful in situations such as:

  • [[<tvar name=1>Special:MyLanguage/Help:Categories</tvar>|Categorizing]] pages which include the template. Note: when changing the categories applied by a template in this fashion, the categorization of the pages which include that template may not be updated until some time later: this is handled by the {{<tvar name=2>ll|Manual:Job queue</tvar>|job queue}}. To force the re-categorization of a particular page, open that page for editing and save it without changes.</translate>

<translate>

  • Ensuring that the template's code is not executed when viewing the template page itself. Typically this is because it expects parameters, and its execution without parameters has an undesired result.

</translate>

<translate> Everything outside <tvar name=noinclude>Template:Tag</tvar> and <tvar name=includeonly>Template:Tag</tvar> is processed and displayed normally; that is, both when the template page is being viewed directly and when the template is included in another page.</translate> <translate> The focus is on what is inside these two tags.</translate>

<translate> Everything outside <tvar name=onlyinclude>Template:Tag</tvar> tags is discarded in the transclusion.</translate> <translate> Even sections tagged includeonly are discarded in the transclusion unless they are also tagged as onlyinclude.</translate> <translate> The focus is only on what is inside this tag.</translate>

For example, if a page like Help:Templates/onlyinclude demo has the wikitext: 

abc<onlyinclude>def</onlyinclude>ghi<includeonly>jkl</includeonly>

The result of transcluding it is def.

<translate> Nesting of these tags is also possible. </translate>

<translate> The three partial transclusion tags enable all possible combinations of what is processed and rendered.</translate> <translate> Comments also fill a role.</translate> <translate> Inclusion tags are respected when using <tvar name="1">{{subst:templatename}}</tvar>, but they are not respected when using <tvar name="2">{{msgnw:templatename}}</tvar> as that displays the raw wikitext without any processing.</translate>

Section transclusion

To transclude different sections of a template on different pages, you can wrap the content in onlyinclude tags and use an if statement on parameters to select which section.

Consider "Template:Example" with this wikitext: 

== Section 1 ==
{{#ifeq:{{{1|1}}}|1|
Content of section one.
}}
{{#ifeq:{{{1|2}}}|2|
== Section 2 ==
Content of section two.
}}

This will render both sections on the example page itself, and allow other pages to transclude the first section with {{example|1}} and the second section with {{example|2}}.

Another approach is to use literal parameter syntax instead: 

{{{section1|
== Section 1 ==
Content of section one.
}}}
{{{section2|
== Section 2 ==
Content of section two.
}}}

Transclude the first section with {{example|section2=}} and the second section with {{example|section1=}}. If neither parameter is used, then both sections will display.

A third approach is to use Labeled Section Transclusion. <translate>

Organizing templates

For templates to be effective, users need to find them, and find out how to use them.

To find them, users can:

  1. Click <tvar name=special>Template:Int</tvar> > <tvar name=all>Template:Int</tvar>
  2. In the <tvar name=ns>Template:Int</tvar> list, choose Template and click <tvar name=submit>Template:Int</tvar>.

To give usage information, include an example like this one on the template page: 

<noinclude>
== Usage ==
Welcome users:
{{Thankyou|reason=your reason|signature=your signature}}
</noinclude>

Then, an editor can simply copy and paste the example to use the template. </translate>

<translate> While editing a page, a list of all templates used is available under the editing form, in a collapsible section titled "<tvar name=1>Template:Int</tvar>" (also named "<tvar name=2>Template:Int</tvar>", or "<tvar name=3>Template:Int</tvar>" depending on the context).</translate> <translate> This list provides a convenient link to the template's page, as well as information about its protection status.</translate> <translate> Redirected templates are shown in italics, with the redirect target added as a separate list item.</translate>

<translate>

Linking to a template

A template page can be linked to like any other wiki page. For example, the link <tvar name=navbarlink>Template:Navbar</tvar> is generated using the wikicode <tvar name=navbarcode>[[Template:Navbar]]</tvar>.

On many wikis, <tvar name=1>Template:Tl</tvar> can be used to provide a link to a template formatted in a way that shows the "double curly-braces" wikicode necessary to transclude the template without actually doing the tranclusion. For example, the code <tvar name=2>{{tl|Navbar}}</tvar> may be used to create the link <tvar name=3>{{Navbar}}</tvar>. </translate>

<translate> This construct is commonly used when referring to templates in template documentation, on help pages, and on talk pages.</translate> <translate> The same effect can be achieved by using <tvar name=1>{{[[Template:Navbar|Navbar]]}}</tvar>, but the <tvar name=2>{{tl}}</tvar> approach involves much less typing.</translate> <translate> On any given wiki the Tl template, if it exists, may or may not render the text in a "code" element or as monospace type.</translate> <translate> If not (as on this wiki), another similarly named template may do so.</translate> <translate> See, for example, the [[<tvar name=1>Template:Tl#See also</tvar>|"See also" section of our Template:Tl documentation]].</translate>

Template naming

The name of a template is case-sensitive excluding the first character.

You make redirects for alternate capitalizations. For example, if a template is named "AdminAbbr", you can create a redirect named "Adminabbr". This way, the template can be called with either {{AdminAbbr}} or {{adminabbr}}. If an editor prefers a mix of upper and lower case for clarity, they can use functions like lc or uc. For instance, instead of {{CURRENTINTERNETTIME}}, they could use {{ {{uc:CurrentInternetTime}} }}

Because template names are interpreted in the same way to the names of other pages, underscores are replaced with spaces, and any text after a number sign (what would be a anchor in a standard link) is ignored.

An underscore _ can be alternative to a blank space.

Possible uses of templates

Templates can be used for any situation in which one wants two or more pages to contain identical or similar content that is edited together rather than independently. They can be used to: 

   |Template:Anchor (or Anchors): too many anchors, maximum is ten}}}} }} }} }} }} }} }} }} }} }} Build composite pages that display the content of multiple existing pages together, like w:WP:Village pump (all) which includes content from each section of the village pump. The content of these pages can either be shown individually, or together, but the revision history, watchlist, etc. will only pick up changes to the transcluded pages and the raw wikitext of the composite page itself, not implicit changes to the composite page.
  • Share some content between a few related pages. For example, the list at Help:Preferences#Beta features is duplicated at Beta Features#Current Beta Features. While on MediaWiki.org that is built using Extension:LabeledSectionTransclusion instead, it could have been done using a template.
  • Store content referenced multiple times on the same page, so it only has to be written and calculated once. For example w:Template:Cite Monumentenregister/URL is called twice by w:Template:Cite Monumentenregister in two different places, and using another template means the URL pattern only has to be written once in the base template.
  • Use templates as a programming element to generate a loop: if Template:A calls Template:B 10 times with different parameters, then that crudely simulates a for loop. If Template:B calls Template:C 10 times, then you have a nested loop of 100 calls of Template:C. But keep in mind that it is easy to run into the template limits when using templates as advanced programming constructs, and using Scribunto is generally clearer and easier to follow.

<translate>

Copying from one wiki to another

</translate> It is possible, if {{#ifeq:Manual:$wgEnableScaryTranscluding| 

 |

}}{{#if:allowed by the wiki configuration |allowed by the wiki configuration |allowed by the wiki configuration}}{{#ifeq:Manual:$wgEnableScaryTranscluding| 

 |

}} to transclude templates from other wikis. This configuration setting is disabled on Wikimedia wikis. Otherwise, you need to manually copy the template and its dependencies from the source wiki to the destination wiki to use it.

<translate> Templates often require [[<tvar name=1>Special:MyLanguage/Manual:Interface/Stylesheets</tvar>|CSS]] or other templates, so users frequently have trouble copying templates from one wiki to another. The steps below should work for most templates.

MediaWiki code

If you have import rights (specifically importupload) on the new wiki:

  1. Go to <tvar name=export>Special:Export</tvar> on the original wiki, and download an .xml file with the complete history of all necessary templates, as follows:</translate>

<translate>

    • Enter the name of the template in the big text box, e.g. "Template:Welcome". Pay special attention to capitalization and special characters — if the template name isn't exactly correct, the export may still occur but the .xml file will not have the expected data.</translate>

<translate>

    • Select the box "<tvar name=export>Template:Int</tvar>".</translate>

<translate>

    • Select the box "<tvar name=export2>Template:Int</tvar>".</translate>

<translate>

<translate>

  1. Go to Special:Import on the new wiki and upload the .xml file.

If you don't have import rights on the new wiki:

  1. Go to the template you want to copy from the original wiki. Go to the edit page, and copy all the wikitext</translate>

<translate>

  1. On the new wiki, go to the page with the same name as the template you copied. Hit create/edit and paste the wikitext you copied. In the edit summary of each template, link to the original page for attribution.</translate>

<translate>

  1. Back in the original wiki at the edit window, below the edit box, look at the list of "Templates used on this page". For each template listed follow these instructions. Also do that for any template used by any of these templates, and so on.

</translate>

<translate> This will copy the entire code necessary, and will suffice for some templates.</translate> <translate> Note that only page elements parsed in rendering the page get exported, consequently documentation subpages are not exported as part of this process.</translate> <translate> If it doesn't work also check for red links listed under "Pages transcluded onto the current version of this page:", below the edit box. If there are any repeat the above steps for these as well and also copy the code in the modules.</translate>

<translate> After successfully importing the template and all its linked templates from the other wiki, edit it to change customisations to suit your wiki. For example to change a logo, remove redundant categories or red links.

Extensions

</translate> <translate> An extension often used in templates is ParserFunctions.</translate> <translate> Visit page <tvar name=1>{{#ifeq:Help:Extension:ParserFunctions| 

 |

}}[[Special:MyLanguage/Help:Extension:ParserFunctions|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Help|Help:}}Extension:ParserFunctions/Page display title/en 

 |{{#ifexpr:{{#if:0|1|0}} and 12!=0
   |{{#ifeq:en|en
     |Extension:ParserFunctions
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Help:Extension:ParserFunctions
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:0
   |{{#if:Extension:ParserFunctions
     |Extension:ParserFunctions
     |Help:Extension:ParserFunctions
   }}
   |Help:Extension:ParserFunctions
 }}

}}}}]]{{#ifeq:Help:Extension:ParserFunctions| 

 |

}} </tvar> and check if any of the functions listed there are used in the templates you've copied.</translate> <translate> If so, you have to install the <tvar name=1>{{#ifeq:Extension:ParserFunctions| 

 |

}}[[Special:MyLanguage/Extension:ParserFunctions|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:|:}}Extension:ParserFunctions/Page display title/en 

 |{{#ifexpr:{{#if:0|1|0}} and 0!=0
   |{{#ifeq:en|en
     |Extension:ParserFunctions
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Extension:ParserFunctions
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:0
   |{{#if:Extension:ParserFunctions
     |Extension:ParserFunctions
     |Extension:ParserFunctions
   }}
   |Extension:ParserFunctions
 }}

}}}}]]{{#ifeq:Extension:ParserFunctions| 

 |

}} </tvar> extension.</translate> <translate> To install it, you'll need system admin access to the server of your MediaWiki installation.</translate>

<translate> Another dependency that may be used in templates, especially those on Wikipedia, is Lua. Having <tvar name=invoke>{{#invoke: }}</tvar> in template code is a good sign for it.</translate> <translate> In case it's used, you need to install the <tvar name=1>{{#ifeq:Extension:Scribunto| 

 |

}}[[Special:MyLanguage/Extension:Scribunto|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:|:}}Extension:Scribunto/Page display title/en 

 |{{#ifexpr:{{#if:0|1|0}} and 0!=0
   |{{#ifeq:en|en
     |Extension:Scribunto
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Extension:Scribunto
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:0
   |{{#if:Extension:Scribunto
     |Extension:Scribunto
     |Extension:Scribunto
   }}
   |Extension:Scribunto
 }}

}}}}]]{{#ifeq:Extension:Scribunto| 

 |

}} </tvar> extension and system admin access is required too.</translate> <translate> See that page for more instructions about installing and using the extension.</translate>

<translate>

CSS and JavaScript code

Besides MediaWiki code, many templates make use of CSS and some rely on JavaScript to work fully. If the copied templates are not behaving as expected, this may be the cause. To copy the required CSS and JavaScript to your wiki you'll normally need to have admin privileges, because you'll be editing system messages in the "MediaWiki:" namespace.

  1. Look for the use of CSS classes (text like class="foobar") in the template text. If those classes appear in "MediaWiki:Common.css" or "MediaWiki:Monobook.css" on the original wiki, copy those classes to "MediaWiki:Common.css" on the new wiki and check if the template is now fine.</translate>

<translate>

  1. If the copied template is still not working as expected, check if there is code in "MediaWiki:Common.js" or "MediaWiki:Monobook.js" on the original wiki. If so, you can try copying it to "MediaWiki:Common.js" on the new wiki. Normally, it is a good idea to only copy code from trusted sources, and browse the code to identify and select the relevant parts. You may find comments that can serve as clues to identify the functionality of each part.

Redirection

</translate> If a page uses a redirect as a template, the redirect is resolved before processing the template and the target is used instead. This won't work if the target doesn't exist (a broken redirect), or is itself a redirect (a double redirect).

A page that just includes another page as a template might look like a redirect, but there are several differences between them:

  • The header of the result displays the title of the page it came from.
  • No "Redirected from" message is shown.
  • Buttons like edit, watch, talk, history, "what links here," and "last modified" point to the referring page. To access the target page, use a section edit link and navigate from there.
  • Unless includeonly and/or noinclude tags are used, the referring page shares the same categories as the target page.
  • "Double redirects" work when one or both are this type of pseudo-redirect.

{{#if: |

|Note}} Note: {{#if: |{{{1}}}

}}

Parser functions

Main article{{#if:|s}}: Help:Parser functions{{#if: 
 |{{#if:|, | and }}[[{{{2}}}]]}}{{#if:
 |{{#if:|, |, and }}[[{{{3}}}]]}}{{#if:
 |{{#if:|, |, and }}[[{{{4}}}]]}}{{#if:

|, and [[{{{5}}}]]}}{{#if: | (too many parameters in {{main}})}}

MediaWiki also supports parser functions, which function similarly to templates but follow slightly different syntax:

  • Parser functions utilize a ":" instead of the initial "|".
  • An edit page does not display parser functions used on that page.
  • There is no "What links here" feature for parser functions to identify the pages where they are utilized.
  • Parser functions templates do not generally accept named parameters, so equal signs generally have no special significance. For example:
{{ #if: not blank | x=abc }} gives x=abc

<translate>

See also

General template usage

</translate> 

 |

}}[[Special:MyLanguage/Manual:Advanced templates|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:|:}}Manual:Advanced templates/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 0!=0
   |{{#ifeq:en|en
     |Manual:Advanced templates
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Manual:Advanced templates
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Manual:Advanced templates
     |Manual:Advanced templates
     |Manual:Advanced templates
   }}
   |Manual:Advanced templates
 }}

}}}}]]{{#ifeq:Manual:Advanced templates| 

 |

}} – <translate> describes even more advanced techniques such as dynamic template calls and variable parameter names</translate>

  • {{#ifeq:Help:Multiple-instance templates|
 |

}}[[Special:MyLanguage/Help:Multiple-instance templates|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Help|Help:}}Multiple-instance templates/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 12!=0
   |{{#ifeq:en|en
     |Multiple-instance templates
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Help:Multiple-instance templates
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Multiple-instance templates
     |Multiple-instance templates
     |Help:Multiple-instance templates
   }}
   |Help:Multiple-instance templates
 }}

}}}}]]{{#ifeq:Help:Multiple-instance templates| 

 |

}} - on the use of multiple instances of the same template on a page.

<translate>

Special constructs used in templates

</translate>

  • {{#ifeq:Help:Magic words|
 |

}}[[Special:MyLanguage/Help:Magic words|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Help|Help:}}Magic words/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 12!=0
   |{{#ifeq:en|en
     |Magic words
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Help:Magic words
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Magic words
     |Magic words
     |Help:Magic words
   }}
   |Help:Magic words
 }}

}}}}]]{{#ifeq:Help:Magic words| 

 |

}} – <translate> fancy stuff you may find in some templates</translate>

  • {{#ifeq:Help:Extension:ParserFunctions|
 |

}}[[Special:MyLanguage/Help:Extension:ParserFunctions|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Help|Help:}}Extension:ParserFunctions/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 12!=0
   |{{#ifeq:en|en
     |Extension:ParserFunctions
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Help:Extension:ParserFunctions
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Extension:ParserFunctions
     |Extension:ParserFunctions
     |Help:Extension:ParserFunctions
   }}
   |Help:Extension:ParserFunctions
 }}

}}}}]]{{#ifeq:Help:Extension:ParserFunctions| 

 |

}} – <translate> additional fancy control functions such as <tvar name=if>#if</tvar> and <tvar name=switch>#switch</tvar></translate>

  • {{#ifeq:Help:Parser functions in templates|
 |

}}[[Special:MyLanguage/Help:Parser functions in templates|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Help|Help:}}Parser functions in templates/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 12!=0
   |{{#ifeq:en|en
     |Parser functions in templates
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Help:Parser functions in templates
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Parser functions in templates
     |Parser functions in templates
     |Help:Parser functions in templates
   }}
   |Help:Parser functions in templates
 }}

}}}}]]{{#ifeq:Help:Parser functions in templates| 

 |

}} – <translate> guidance on using parser functions in templates</translate>

  • {{#ifeq:Help:TemplateData|
 |

}}[[Special:MyLanguage/Help:TemplateData|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Help|Help:}}TemplateData/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 12!=0
   |{{#ifeq:en|en
     |TemplateData
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Help:TemplateData
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:TemplateData
     |TemplateData
     |Help:TemplateData
   }}
   |Help:TemplateData
 }}

}}}}]]{{#ifeq:Help:TemplateData| 

 |

}}

  • {{#ifeq:Help:Extension:ParserFunctions|
 |

}}[[Special:MyLanguage/Help:Extension:ParserFunctions|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Help|Help:}}Extension:ParserFunctions/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 12!=0
   |{{#ifeq:en|en
     |Extension:ParserFunctions
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Help:Extension:ParserFunctions
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Extension:ParserFunctions
     |Extension:ParserFunctions
     |Help:Extension:ParserFunctions
   }}
   |Help:Extension:ParserFunctions
 }}

}}}}]]{{#ifeq:Help:Extension:ParserFunctions| 

 |

}}

  • {{#ifeq:Extension:Scribunto|
 |

}}[[Special:MyLanguage/Extension:Scribunto|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:|:}}Extension:Scribunto/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 0!=0
   |{{#ifeq:en|en
     |Extension:Scribunto
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Extension:Scribunto
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Extension:Scribunto
     |Extension:Scribunto
     |Extension:Scribunto
   }}
   |Extension:Scribunto
 }}

}}}}]]{{#ifeq:Extension:Scribunto| 

 |

}}

<translate>

Other relevant information

</translate>

  • {{#ifeq:Help:ExpandTemplates|
 |

}}[[Special:MyLanguage/Help:ExpandTemplates|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Help|Help:}}ExpandTemplates/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 12!=0
   |{{#ifeq:en|en
     |ExpandTemplates
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Help:ExpandTemplates
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:ExpandTemplates
     |ExpandTemplates
     |Help:ExpandTemplates
   }}
   |Help:ExpandTemplates
 }}

}}}}]]{{#ifeq:Help:ExpandTemplates| 

 |

}}

  • {{#ifeq:Help:External searches|
 |

}}[[Special:MyLanguage/Help:External searches|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Help|Help:}}External searches/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 12!=0
   |{{#ifeq:en|en
     |External searches
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Help:External searches
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:External searches
     |External searches
     |Help:External searches
   }}
   |Help:External searches
 }}

}}}}]]{{#ifeq:Help:External searches| 

 |

}} – <translate> a template special use case example</translate>

  • {{#ifeq:Manual:Importing Wikipedia infoboxes tutorial|
 |

}}[[Special:MyLanguage/Manual:Importing Wikipedia infoboxes tutorial|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:|:}}Manual:Importing Wikipedia infoboxes tutorial/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 0!=0
   |{{#ifeq:en|en
     |Manual:Importing Wikipedia infoboxes tutorial
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Manual:Importing Wikipedia infoboxes tutorial
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Manual:Importing Wikipedia infoboxes tutorial
     |Manual:Importing Wikipedia infoboxes tutorial
     |Manual:Importing Wikipedia infoboxes tutorial
   }}
   |Manual:Importing Wikipedia infoboxes tutorial
 }}

}}}}]]{{#ifeq:Manual:Importing Wikipedia infoboxes tutorial| 

 |

}}

  • {{#ifeq:Extension:PageTemplates|
 |

}}[[Special:MyLanguage/Extension:PageTemplates|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:|:}}Extension:PageTemplates/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 0!=0
   |{{#ifeq:en|en
     |Extension:PageTemplates
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Extension:PageTemplates
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Extension:PageTemplates
     |Extension:PageTemplates
     |Extension:PageTemplates
   }}
   |Extension:PageTemplates
 }}

}}}}]]{{#ifeq:Extension:PageTemplates| 

 |

}}

  • {{#ifeq:Manual:Creating pages with preloaded text|
 |

}}[[Special:MyLanguage/Manual:Creating pages with preloaded text|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:|:}}Manual:Creating pages with preloaded text/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 0!=0
   |{{#ifeq:en|en
     |Manual:Creating pages with preloaded text
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Manual:Creating pages with preloaded text
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Manual:Creating pages with preloaded text
     |Manual:Creating pages with preloaded text
     |Manual:Creating pages with preloaded text
   }}
   |Manual:Creating pages with preloaded text
 }}

}}}}]]{{#ifeq:Manual:Creating pages with preloaded text| 

 |

}} – <translate> Using templates as the starting text of a page</translate>

  • {{#ifeq:Help:Transclusion|
 |

}}[[Special:MyLanguage/Help:Transclusion|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Help|Help:}}Transclusion/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 12!=0
   |{{#ifeq:en|en
     |Transclusion
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Help:Transclusion
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Transclusion
     |Transclusion
     |Help:Transclusion
   }}
   |Help:Transclusion
 }}

}}}}]]{{#ifeq:Help:Transclusion| 

 |

}} – <translate> embedding pages from [[<tvar name=ns>Special:MyLanguage/Help:Namespaces</tvar>|namespaces]] other than Template:</translate>

  • {{#ifeq:Manual:Template limits|
 |

}}[[Special:MyLanguage/Manual:Template limits|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:|:}}Manual:Template limits/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 0!=0
   |{{#ifeq:en|en
     |Manual:Template limits
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Manual:Template limits
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Manual:Template limits
     |Manual:Template limits
     |Manual:Template limits
   }}
   |Manual:Template limits
 }}

}}}}]]{{#ifeq:Manual:Template limits| 

 |

}}

  • {{#ifeq:Help:What links here|
 |

}}[[Special:MyLanguage/Help:What links here|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Help|Help:}}What links here/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 12!=0
   |{{#ifeq:en|en
     |What links here
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Help:What links here
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:What links here
     |What links here
     |Help:What links here
   }}
   |Help:What links here
 }}

}}}}]]{{#ifeq:Help:What links here| 

 |

}} 

 |

}}[[Special:MyLanguage/Manual:$wgEnableScaryTranscluding|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:|:}}Manual:$wgEnableScaryTranscluding/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 0!=0
   |{{#ifeq:en|en
     |Manual:$wgEnableScaryTranscluding
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Manual:$wgEnableScaryTranscluding
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Manual:$wgEnableScaryTranscluding
     |Manual:$wgEnableScaryTranscluding
     |Manual:$wgEnableScaryTranscluding
   }}
   |Manual:$wgEnableScaryTranscluding
 }}

}}}}]]{{#ifeq:Manual:$wgEnableScaryTranscluding| 

 |

}} - using templates from other wikis 

 |

}}[[Special:MyLanguage/Help:Extension:TemplateSandbox|{{#if: |{{{2}}} |{{#ifexist:Translations:{{#if:Help|Help:}}Extension:TemplateSandbox/Page display title/en 

 |{{#ifexpr:{{#if:|1|0}} and 12!=0
   |{{#ifeq:en|en
     |Extension:TemplateSandbox
     |{{#if:
        |{{#ifeq:{{#invoke:string|find||:}}|0
          |
          | {{#invoke:string|match||:(.*)}}
        }}
        |{{#if:{{ Template:TNTN | nsp = 0 }}
          |{{ Template:TNTN | nsp = 0 }}
          |Help:Extension:TemplateSandbox
       }}
     }}
   }}
   |{{ Template:TNTN }}
 }}
 |{{#if:
   |{{#if:Extension:TemplateSandbox
     |Extension:TemplateSandbox
     |Help:Extension:TemplateSandbox
   }}
   |Help:Extension:TemplateSandbox
 }}

}}}}]]{{#ifeq:Help:Extension:TemplateSandbox| 

 |

}} - for previewing your changes to a template as it renders elsewhere

<translate>

External links

</translate>

Template:Help

[[Category:Help{{#translation:}}|Templates]] [[Category:Template{{#translation:}}]] [[Category:MediaWiki for site admins{{#translation:}}]]

Retrieved from "https://nick-black.com/dankwiki/index.php?title=Help:Templates&oldid=11325"