Manual:Extension registration/Limitations

Extension registration does have known limitations that may make it unsuitable to convert your extension immediately. Some of these are intentional, and others are just waiting for a developer to implement them :)


 * Configuration settings must have a prefix of "wg": T97186
 * PHP Constants are not supported. The rationale for this is constants are either used in LocalSettings.php when raw strings should be used instead (you can't use constants in a configuration database), or in code, when they should instead be a part of a class.
 * Configuration settings that are 2d arrays or deeper do not merge properly: T99257
 * Conditional namespaces are not supported: ???

The workaround for much of this is to use custom registration. If you find something you can't do, create a Phabricator task.