- In the extension I can made a file ext.i18n.php and then use:
$wgExtensionMessagesFiles['ext'] = dirname( __FILE__ ) . 'ext.i18n.php'; wfMsg('something');
In the interest of keeping up with the times, I'll leave this here:
http://www.mediawiki.org/wiki/WfMessage#Comparison_with_the_deprecated_wfMsg...
Not to say that you should necessarily rush to "fix" your extensions, but be aware that it's preferable to use the wfMessage function now.
Credit to Krenair, by the way, who managed to merge a fix for my bug report about this in less than three hours (the patch is also a good example of how to update your extensions):
https://bugzilla.wikimedia.org/show_bug.cgi?id=38501
Cheers,