Translations:Manual:Extension registration/76/en

Check, if an extension is loaded without actually require it
Many extension may provide features, which only works, if another extension is loaded, too, without really needing this feature for the core extension function to work. As an example: If extension B is loaded, extension A can provide a real WYSIWYG editor, otherwise it will use a simple textarea. Extension A can profit from extension B (if it is loaded), but doesn't require it to be loaded to work properly. For this, you generally check, if the extension is loaded, rather than adding it as a hard dependency.