Wikipedia:Substitution: Difference between revisions

'''Substitution''' is a different way of handling [[WP:Templates|templates]] than normally done on Wikipedia. Usually, templates are [[WP:Transclusion|transcluded]], which means that if the template changes, every page that uses it will update to comply with the change-in-question. This is the procedure used for most templates. However, some templates are instead substituted. This means that if the template changes, the page that uses it will not, and will continue to show the old version of the template. Some templates should always be substituted, while most should always be transcluded.

 

 

This page also lists templates that should either always or never be substituted except in the Wikipedia namespace. Automated tools (a.k.a. [[WP:Bots|bots]]) that do such replacements will <em>never</em> be used on the original template. If you are going to use a bot to substitute templates, please read through [[Wikipedia talk:Substitution|the talk page]] first, as many are under dispute or change status over time, and substitution is permanent.

 

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Ordinarily, a template will be expanded "on the fly"; that is, the template code on a page calls a separate page every time it is rendered. Although most page views are served from the cache, pages need to be rendered for previews and rendered again when the page changes. When someone is editing a page with a normal template call, they see the template call.

 

 

 

 

{{Anchor|Hidden comment}}Additionally, when creating or editing templates that are commonly substituted, adding a hidden comment to the template page helps article editors to see how templates are being used (e.g. <code>&lt;!-- Substituted from [[Template:Documentation]] --></code>). Use {{tls|html comment}} if you want to write HTML comments that contain wikitext expansions.

 

* If there is a template you would like to modify for a single occasion, but you do not want to modify the template for all the pages that use it, and you do not want to make a new template, you can substitute the template and then with a second edit, make the modifications. For example, a template might be used with all the states of the United States and with the District of Columbia. The template might be worded correctly for the states, but not for DC. To fix the wording, you can substitute the template and then fix the wording.

* Substituting frequently used, but unprotected templates, limits the damage that can be caused by people [[WP:Vandalism|vandalizing]] the template. See [[WP:high-risk templates|high-risk templates]].

* Substitution allows for recursive evaluation through macro templates.

 

* Substituting ''en masse'' <strong>may</strong> ultimately speed up the site, but this is not a reason to prefer substitution over transclusion. [[WP:Don't worry about performance|Don't worry about performance]] of Wikipedia's servers.

* Templates are often modified or deleted. If a template is [[WP:Glossary#Boilerplate text|boilerplate text]], consider whether you want it to vary as the template is modified. If your answer is "no", substitution is warranted. An example of this is the {{tls|welcome}} template. The archives of a user's talk page should show the actual welcome message they received, not the current welcome message.

 

* Once a template is substituted, the result is no longer linked to the template, making it hard to find all pages displaying that text (though categories can sometimes relieve this). The problem can easily be worked around by including a link to the template in the template's code.

* A substituted template will not be updated when errors in the master template are corrected.

* Some meta-templates, such as {{tn|!}} and {{tl|((}}, do not work if they are substituted.

 

This is a list of templates that should always be substituted, organized by [[WP:Namespace|namespace]]. Each list is ordered alphabetically with grouped series. '''This is not a comprehensive list'''; other less-used templates may also need to be substituted, see the template's documentation for details.

 

* {{tl|No more links}}, substituting this inserts a commentary only visible in edit mode, with a short explanation to discourage spamming links.

 

* {{tl|tmfrom}}, {{tl|tmto}}

 

All of the templates listed in [[:Category:User warning templates]] and [[:Category:Welcome templates]] should be substituted. This does not apply to templates on the user page.

 

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* User signature templates, if transcluded, cause undue server strain as changes to a minor user template must then be widely propagated. If used, user signature templates should be substituted. (It should be noted, however, that [[WP:SIG#NT|user signature templates are discouraged]].)

 

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{{Anchor|Must}}{{shortcut|WP:SUBSTMUST}}

These templates have a purpose and/or syntax that require them to be substituted.

* {{tl|OnProd}}, which inserts today's-date-dependent name of the category page to which the article was added when nominated for deletion.

 

{{Anchor|Not}}{{shortcut|WP:SUBSTNOT}}

Technically, templates should not be substituted that:

<li>contain external links as the formatting of the URL to perform queries or look-ups may change

</ol>

If specific [[WP:CON|consensus]] is to eliminate a particular call of such a template, [[Special:ExpandTemplates]] can be used to expand that call to plain wiki-syntax.

 

This is a list of templates that should not be substituted. This is because they contain formatting standard code, complex code, or code that breaks if substituted.

* Various citation/reference templates which contain very complex conditional code (see: [[WP:CITET]]).

* [[:Category:Infobox templates|Infobox templates]], various ones for the sake of bot-identification and consistency.

* {{tl|Javadoc:EE}}, {{tl|Javadoc:SE}}, {{tl|Javadoc:SE-guide}}, conditional templates whose purpose is to update the links when the master template is updated.

Note also that some things may appear to be templates but are actually [[Help:Magic words|magic words]], such as {{tlf|!}} and {{tlf|noexternallanglinks}}. Substituting them either will output nothing, or will substitute a template that [[variable shadowing|shadows]] them (like the deprecated [[Template:!]]).

 

These templates, used in the main-space, add a comment about why an article is misnamed. They may be removed as the MediaWiki titling facilities improve, and the wording/layout may change.

* {{tl|correct title}}

* {{tl|lowercase}}

 

Most templates related to renaming or deleting pages are used temporarily, and thus do not need to be substituted (it just makes more work to delete them).

* {{tl|catfd}}

* {{tl|archive top}} {{tl|archive bottom}}, {{tl|discussion top}} {{tl|discussion bottom}}

 

{{Wikipedia glossary}}

* [[Help:Substitution]]