In MW 1.24 an effort was made to improve code quality by making it phpcs-strict compliant [0]. This involves explicitly declaring the visibility of class members. In the course of this, in many cases the class variable's visibility was changed from the implicit 'public' to explicit 'protected' or 'private', thus introducing a major API change without proper deprecation period.
To keep the changes and still be able to properly deprecate the direct access to the member variables a patch [1] was submitted that makes use of PHP magic functions [2]. The introduced functions provide access to the formerly public class members and issue a deprecation warning. For old PHP versions a warning by Tim Starling existed [4], to avoid __get(). However, this does not apply to the current case, as the __get method is not used re-entrantly. Moreover, it is questionable, whether this warning is still valid for recent versions of PHP.
[0] https://gerrit.wikimedia.org/r/#/q/status:merged+project:mediawiki/core+branch:master+topic:phpcs,n,z
[1] https://gerrit.wikimedia.org/r/#/c/151370/
[2] http://php.net/manual/en/language.oop5.overloading.php#language.oop5.overloading.members
[3] https://www.mediawiki.org/wiki/Deprecation
[4] https://www.mediawiki.org/wiki/Special:Code/MediaWiki/85288#c17504
The intention is to keep these functions for the custom two releases [3], i.e. until 1.26, and then remove them.
Affected classes, files and action required for removal:
- CategoryViewer (CategoryViewer.php; delete magic functions)
- EditPage (EditPage.php; delete magic functions)
- WikiExporter (Export.php; delete magic functions)
- DumpLatestFilter (Export.php; delete magic functions)
- FeedItem (Feed.php; delete magic functions)
- DiffHistoryBlob (HistoryBlob.php; delete magic functions)
- WikiRevision (Import.php; delete magic functions)
- Article (Article.php; delete magic functions __isset() and __unset(), modify __get() and __set() to not return private variables of Article anymore)