bdddfb92ba
Bug: T245940 Depends-On: Ib7fe7318100c0aadc3aa759416bf787913a9b788 Change-Id: I75c3b6715abd5eaf3619337cab8b1844e9a8349a
60 lines
2 KiB
Text
60 lines
2 KiB
Text
globals.txt
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Globals are evil. The original MediaWiki code relied on globals for processing
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context far too often. MediaWiki development since then has been a story of
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slowly moving context out of global variables and into objects. Storing
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processing context in object member variables allows those objects to be reused
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in a much more flexible way. Consider the elegance of:
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# Generate the article HTML as if viewed by a web request
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$article = new Article( Title::newFromText( $t ) );
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$article->view();
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versus
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# Save current globals
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$oldTitle = $wgTitle;
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$oldArticle = $wgArticle;
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# Generate the HTML
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$wgTitle = Title::newFromText( $t );
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$wgArticle = new Article;
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$wgArticle->view();
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# Restore globals
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$wgTitle = $oldTitle
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$wgArticle = $oldArticle
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Some of the current MediaWiki developers have an idle fantasy that some day,
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globals will be eliminated from MediaWiki entirely, replaced by an application
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object which would be passed to constructors. Whether that would be an
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efficient, convenient solution remains to be seen, but certainly PHP 5 makes
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such object-oriented programming models easier than they were in previous
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versions.
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For the time being though, MediaWiki programmers will have to work in an
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environment with some global context. At the time of writing, 418 globals were
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initialised on startup by MediaWiki. 304 of these were configuration settings,
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which are documented in DefaultSettings.php. There is no comprehensive
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documentation for the remaining 114 globals, however some of the most important
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ones are listed below. They are typically initialised either in index.php or in
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Setup.php.
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$wgTitle
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Title object created from the request URL.
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$wgOut
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OutputPage object for HTTP response.
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$wgUser
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User object for the user associated with the current request.
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$wgLang
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Language object selected by user preferences.
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$wgParser
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Parser object. Parser extensions used to register their hooks here;
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modern code should use the ParserFirstCallInit hook.
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$wgRequest
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WebRequest object, to get request data
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