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<languages/>
{{Magic words}}
{{advanced user manual}}
[[File:MediaWiki-extensions-icon.svg|125px|alt=<span lang="en" dir="ltr" class="mw-content-ltr">MediaWiki extensions</span>|right]]

<span lang="en" dir="ltr" class="mw-content-ltr">'''Magic words''' are strings of text that MediaWiki links to specific functions or return values, such as current date and time, page titles, site information, and more.</span>
<span lang="en" dir="ltr" class="mw-content-ltr">They can be thought of as special commands or variables that allow dynamic content generation and interaction with the MediaWiki software during page rendering.</span>

<span lang="en" dir="ltr" class="mw-content-ltr">From a technical standpoint, magic words map a range of wiki text strings to a unique internal identifier (ID), which is then associated with a particular function.</span>
<span lang="en" dir="ltr" class="mw-content-ltr">This ID directs MediaWiki to execute a corresponding operation or return a specific value. Both '''{{ll|Manual:Variables|variables}}''' (which output dynamic values) and '''{{ll|Manual:Parser functions|parser functions}}''' (which perform operations or conditional logic) make use of this mapping technique.</span>

<span lang="en" dir="ltr" class="mw-content-ltr">All text mapped to that ID will be replaced with the return value of the function.</span>
<span lang="en" dir="ltr" class="mw-content-ltr">The mapping between the text strings and the ID is stored in the variable <code>$magicWords</code> in a file that can be loaded using {{wg|ExtensionMessagesFiles}}.</span>

<div lang="en" dir="ltr" class="mw-content-ltr">
The default magic words are implemented in {{ll|Manual:CoreParserFunctions.php|CoreParserFunctions.php}}.
</div>

<div lang="en" dir="ltr" class="mw-content-ltr">
== How magic words work ==
</div>

<div lang="en" dir="ltr" class="mw-content-ltr">
Whenever MediaWiki finds text between double braces (<code><nowiki>{{</nowiki>XXX ...}}</code>) it must decide whether XXX is a [[Special:MyLanguage/Manual:Variables|variable]], [[Special:MyLanguage/Manual:Parser functions|parser function]], or [[Special:MyLanguage/Help:Templates|template]].  To do so, it asks a series of questions:
</div>

#<span lang="en" dir="ltr" class="mw-content-ltr">'''Does it have an associated magic word ID?''' As a first step in resolving markup of the form <code><nowiki>{{XXX...}}</nowiki></code>, MediaWiki attempts to translate ''XXX'' to a magic word ID. The translation table is defined by <code>$magicWords</code>.</span> 
#*<span lang="en" dir="ltr" class="mw-content-ltr">If no magic word ID is associated with ''XXX'', ''XXX'' is presumed to be a [[Special:MyLanguage/Help:Templates|template]].</span>
#:<br/>
#<span lang="en" dir="ltr" class="mw-content-ltr">'''Is it a variable?''' If a magic word ID <em>is</em> found, MediaWiki next checks to see if it has any parameters.</span> 
#*<span lang="en" dir="ltr" class="mw-content-ltr">If no parameters are found, MediaWiki checks to see if the magic word ID has been declared as a variable ID.</span> <span lang="en" dir="ltr" class="mw-content-ltr">To check this, it retrieves the list of magic words serving by calling <code>MagicWord::getVariableIDs()</code>.</span> <span lang="en" dir="ltr" class="mw-content-ltr">This method gets its list of variable IDs from a hard coded list of variable IDs (see {{ll|Help:Variables}}) and from a list of custom variable IDs provided by all functions attached to the hook {{ll|Manual:Hooks/MagicWordwgVariableIDs|MagicWordwgVariableIDs}}.</span>
#**<span lang="en" dir="ltr" class="mw-content-ltr">If the magic word ID has been classified as a variable, MediaWiki calls the {{ll|Manual:Hooks/ParserGetVariableValueSwitch|ParserGetVariableValueSwitch}} function to get the value associated with the variable name.</span>
#:<br/>
#<span lang="en" dir="ltr" class="mw-content-ltr">'''Is it a parser function?''' If there are any parameters or if the magic word ID is missing from the list of variable magic word IDs, then MediaWiki assumes that the magic word is a [[Special:MyLanguage/Manual:Parser functions|parser function]] or [[Special:MyLanguage/Help:Templates|template]].</span> <span lang="en" dir="ltr" class="mw-content-ltr">If the magic word ID is found in the list of declared parser functions, it is treated as a parser function and rendered using the function named <code>$renderingFunctionName</code>.</span> <span lang="en" dir="ltr" class="mw-content-ltr">Otherwise, it is presumed to be a template.</span>

<div lang="en" dir="ltr" class="mw-content-ltr">
== Defining magic words ==
</div>
{{note
| 2 = reminder
| 1 = <span lang="en" dir="ltr" class="mw-content-ltr">'''When defining or translating magic words, adhere to established conventions'''.</span>

<div lang="en" dir="ltr" class="mw-content-ltr">
By convention:
</div>

* <span lang="en" dir="ltr" class="mw-content-ltr">The magic words called variables are capitalised, case-sensitive, and do not have space characters.</span>
* <span lang="en" dir="ltr" class="mw-content-ltr">Parser functions are prefixed with a hash sign (<nowiki>#</nowiki>), are case insensitive, and do not include space characters.</span>

<div lang="en" dir="ltr" class="mw-content-ltr">
This is however a convention and one not consistently applied (for historic reasons).
</div>

* <span lang="en" dir="ltr" class="mw-content-ltr">Variables do not have spaces in English, but some translations of variables in other languages '''do''' have spaces.</span>
* <span lang="en" dir="ltr" class="mw-content-ltr">Variables generally are capitalised and case-sensitive, but some parser functions also use this convention.</span>
* <span lang="en" dir="ltr" class="mw-content-ltr">Some parser functions start with a hash sign, but some do not.</span>

<span lang="en" dir="ltr" class="mw-content-ltr">Where possible the conventions for defining or translating magic words should be followed.</span>
<span lang="en" dir="ltr" class="mw-content-ltr">Magic words are higher in priority than templates, so any magic word defined, will block the usage of that defined name as a template.</span>
<span lang="en" dir="ltr" class="mw-content-ltr">Following the conventions avoids creating additional potential naming collisions.</span>
}}

<div lang="en" dir="ltr" class="mw-content-ltr">
For magic words to do their magic we must define two things:
</div>

<div lang="en" dir="ltr" class="mw-content-ltr">
* a mapping between wiki text and a magic word ID
</div>
<div lang="en" dir="ltr" class="mw-content-ltr">
* a mapping between a magic word ID and some PHP function that interprets the magic word.
</div>

<div lang="en" dir="ltr" class="mw-content-ltr">
=== Mapping wiki text to magic word IDs ===
</div>
<span lang="en" dir="ltr" class="mw-content-ltr">The variable <code>$magicWords</code> is used to associate each magic word ID with a language-dependent array that describes all the text strings that mapped to the magic word ID.</span>
<span lang="en" dir="ltr" class="mw-content-ltr">Important: This only sets up the back end i18n mapping, you still have to write other code to make MediaWiki use the magic word for anything.</span>
<span lang="en" dir="ltr" class="mw-content-ltr">Also, make sure that you initialise <code>$magicWords</code> as an empty array before adding language-specific values or you will get errors when trying to load the magic word and will need to rebuild your localisation cache before it will work.</span>

<span lang="en" dir="ltr" class="mw-content-ltr">The first element of this array is an integer flag indicating whether or not the magic word is case sensitive. The remaining elements are a list of text that should be associated with the magic word ID.  If the case sensitive flag is 0, any case variant of the names in the array will match.  If the case sensitive flag is 1, only exact case matches will be associated with the magic word ID.</span>
<span lang="en" dir="ltr" class="mw-content-ltr">Thus the format is <code>$magicWords['en'] = [ 'InternalName' => [ 0, 'NameUserTypes', 'AdditionalAliasUserCanType' ] ];</code></span>

<div lang="en" dir="ltr" class="mw-content-ltr">
This association is created by <code>$magicWords</code> in a file registered using {{Wg|ExtensionMessagesFiles}}.
</div>

<span lang="en" dir="ltr" class="mw-content-ltr">In the example below, a Spanish MediaWiki installation will associate the magic word ID <code>MAG_CUSTOM</code> with "personalizado", "custom", "PERSONALIZADO", "CUSTOM" and all other case variants.</span>
<span lang="en" dir="ltr" class="mw-content-ltr">In an English MediaWiki only "custom" in various case combinations will be mapped to <code>MAG_CUSTOM</code>:</span>

<div lang="en" dir="ltr" class="mw-content-ltr">
File <code>Example.i18n.magic.php</code>:
</div>

<syntaxhighlight lang="php">
<?php

$magicWords = [];

$magicWords['en'] = [
	'MAG_CUSTOM' => [ 0, 'custom' ],
];

$magicWords['es'] = [
	'MAG_CUSTOM' => [ 0, 'personalizado' ],
];
</syntaxhighlight>

<div lang="en" dir="ltr" class="mw-content-ltr">
In part of the <code>{{ll|Manual:Extension registration|extension.json}}</code> file:
</div>

<syntaxhighlight lang="json">
"ExtensionMessagesFiles": {
	"ExampleMagic": "Example.i18n.magic.php"
}
</syntaxhighlight>

<div lang="en" dir="ltr" class="mw-content-ltr">
Note that "ExampleMagic" is a different to the key you would use for a plain internationalisation file (normally just the title of the extension, i.e. "Example"). "Magic" has been appended deliberately so one does not overwrite the other.
</div>

<div lang="en" dir="ltr" class="mw-content-ltr">
==== In inline PHP ====
</div>
<span lang="en" dir="ltr" class="mw-content-ltr">You can associate magic words inline in PHP rather than through a i18n file.</span>
<span lang="en" dir="ltr" class="mw-content-ltr">This is useful when defining hooks in <code>{{ll|Manual:LocalSettings.php|LocalSettings.php}}</code> but should not be done in extensions.</span>

<syntaxhighlight lang="php">
$contentLanguage = MediaWiki\MediaWikiServices::getInstance()->getContentLanguage();
$contentLanguage->mMagicExtensions['wikicodeToHtml'] = ['MAG_CUSTOM', 'custom'];
</syntaxhighlight>

<div lang="en" dir="ltr" class="mw-content-ltr">
=== Associating a magic word ID with a PHP function ===
</div>

<div lang="en" dir="ltr" class="mw-content-ltr">
The mechanism for associating magic word IDs with rendering functions depends on whether the magic word will be used as a [[Special:MyLanguage/Manual:Parser functions|parser function]] or a [[Special:MyLanguage/Manual:Variables|variable]]. For more information, please see:
</div>

* {{ll|Manual:Parser functions}}
* {{ll|Manual:Variables}}

<div lang="en" dir="ltr" class="mw-content-ltr">
=== Localisation ===
</div>

:''<span lang="en" dir="ltr" class="mw-content-ltr">See [[Special:MyLanguage/Help:Magic words#Localisation|Help:Magic words#Localisation]] for help.</span>''

<div lang="en" dir="ltr" class="mw-content-ltr">
You can read more on definition and usage of magic words for localisation at {{ll|Manual:Messages API}}, [[Special:MyLanguage/Manual:Language#Namespaces|Manual:Language#Namespaces]]; [[Special:MyLanguage/Help:System message#Avoid_.7B.7BSITENAME.7D.7D_in_messages|<nowiki>Avoid {{SITENAME}} in messages</nowiki>]].
</div>

<div lang="en" dir="ltr" class="mw-content-ltr">
==Behavior switches (double underscore magic words)==
</div>
<span lang="en" dir="ltr" class="mw-content-ltr">Behavior switches are a special type of magic word. They can be recognised by their use of double underscores (rather than double braces).</span>
<span lang="en" dir="ltr" class="mw-content-ltr">Example:</span>
<code><nowiki>__NOTOC__</nowiki></code>

<span lang="en" dir="ltr" class="mw-content-ltr">These magic words typically do not output any content, but instead change the behavior of a page and/or set a page property.</span>
<span lang="en" dir="ltr" class="mw-content-ltr">These magic words are listed in {{phpi|MagicWordFactory::mDoubleUnderscoreIDs}} and also at [[Special:MyLanguage/Help:Magic words#Behavior switches|Help:Magic words#Behavior switches]].</span>
<span lang="en" dir="ltr" class="mw-content-ltr">The effect of most standard behavior switches is defined in {{phpi|Parser::handleDoubleUnderscore()}}.</span>
<span lang="en" dir="ltr" class="mw-content-ltr">If no specific effect is defined, the magic word will simply set a page property in the <code>page_props</code> table.</span>
<span lang="en" dir="ltr" class="mw-content-ltr">This can also be checked later by testing if <syntaxhighlight lang="php" inline>$parser->getOutput()->getPageProperty( 'MAGIC_WORD' )</syntaxhighlight> is null or the empty string</span>

<div lang="en" dir="ltr" class="mw-content-ltr">
=== Custom behavior switch ===
</div>

<div lang="en" dir="ltr" class="mw-content-ltr">
Here is an example extension implementing a custom <code><nowiki>__CUSTOM__</nowiki></code> behaviour switch
</div>

'''MyExt/extension.json''' - <span lang="en" dir="ltr" class="mw-content-ltr">This is minimal, a real extension would fill out more fields.</span>
<syntaxhighlight lang="json">
{
	"name": "MyExt",
	"type": "parserhook",
    "AutoloadNamespaces": {
		"MediaWiki\\Extension\\MyExt\\": "includes/"
	},
	"Hooks": {
		"GetDoubleUnderscoreIDs": "main",
		"ParserAfterParse": "main" 
	},
	"HookHandlers": {
		"main": {
			"class": "MediaWiki\\Extension\\MyExt\\Hooks"
		}
	},
	"ExtensionMessagesFiles": {
		"MyExtMagic": "MyExt.i18n.magic.php"
	},
	"manifest_version": 2
}
</syntaxhighlight>
'''MyExt/MyExt.i18n.magic.php'''
<syntaxhighlight lang="php">
<?php
$magicWords = [];
$magicWords['en'] = [
	'MAG_CUSTOM' => [ 0, '__CUSTOM__' ],
];
</syntaxhighlight>

'''MyExt/includes/Hooks.php'''
<syntaxhighlight lang="php">
<?php

namespace MediaWiki\Extension\MyExt;

use MediaWiki\Hook\GetDoubleUnderscoreIDsHook;
use MediaWiki\Hook\ParserAfterParseHook;
use MediaWiki\Parser\Parser;
use MediaWiki\Parser\StripState;

class Hooks implements GetDoubleUnderscoreIDsHook, ParserAfterParseHook {
	/**
	 * @param string[] &$doubleUnderscoreIDs
	 * @return bool|void
	 */
	public function onGetDoubleUnderscoreIDs( &$ids ) {
		$ids[] = 'MAG_CUSTOM';
	}

/**
	 * @param Parser $parser
	 * @param string &$text
	 * @param StripState $stripState
	 * @return bool|void
	 */
	public function onParserAfterParse( $parser, &$text, $stripState ) {
		if ( $parser->getOutput()->getPageProperty( 'MAG_CUSTOM' ) !== null ) {
			// Do behavior switching here ...
			// e.g. If you wanted to add some JS, you would do $parser->getOutput()->addModules( [ 'moduleName' ] );
		}
	}
}
</syntaxhighlight>

<div lang="en" dir="ltr" class="mw-content-ltr">
==See also==
</div>
*{{ll|Help:Magic words}} - <span lang="en" dir="ltr" class="mw-content-ltr">List of Variables like <code><nowiki>{{PAGENAME}}</nowiki></code> and <code><nowiki>{{SERVER}}</nowiki></code></span>
*{{ll|Manual:MagicWord.php}}

[[Category:Customization techniques{{#translation:}}|{{PAGENAME}}]]
[[Category:Magic words{{#translation:}}|{{PAGENAME}}]]