Notification mechanism for deprecated actions

[strider72]

Attaching a patch that implements a system for notifying when code uses an action that has been deprecated. The action 'retreive_password' has been marked as deprecated.

Doesn't apply to filters yet.

Also see ​http://core.trac.wordpress.org/ticket/12438

[nacin]

I've been wanting to do this for a while.

I don't think it is a good idea to add this directly to do_action and apply_filters calls, as we need these to perform as fast as possible. Additionally, the patch as attached would break any action that has multiple args attached to it.

Instead, I would suggest we issue a call _deprecated_hook( name of hook, version, replacement, message ) just after the hook is executed, and use did_action() in _deprecated_hook() to see whether we should actually trigger a deprecated_hook_used action and issue the E_NOTICE (if WP_DEBUG).

Might not be a bad idea to use _deprecated_action() and _deprecated_filter(), have one wrap the other, and simply use slightly different messages, just to be clear in both the source code and in the E_NOTICE that is produced.

[strider72]

Okay... here's a thought: Is there a definitive "last" hook in WordPress? Right after that fires we could fire off a function that looks at did_action and compares it to an array of deprecated hooks, and fires _deprecated_filter as needed.

I was first trying to figure how to hook it after the do_action is called, but of course the problem there is that do_action fires even if there are no hooks attached to it.

Would it slow down do_action/apply_filter too much if we simply added an in_array to compare $tag to an array of deprecated hooks?

[strider72]

Note: the patch is still useful for the _deprecated_action and _deprecated_filter functions.

Nacin -- also note that $type does indicate in the error message whether it's an action or filter. If there are other types of hooks it could be wrapped just as _deprecated_action does.

[westi]

Cross referencing with #10441 and closing as a dupe.