Post status transition actions

[ryan]

Add post status transition actions so that plugins can hook into workflow. Example actions:

• draft_to_publish
• pending_to_publish
• private_to_publish
• future_to_publish
• pending_to_draft

etc.

Also add hooks announcing new status.

• draft_post
• draft_page
• publish_post
• publish_page
• pending_post
• future_post

etc.

Finally, add a catch-all transition_post_status hook that passes the old and new status.

see #5797

[5797] rather

publish_post is being added in default_filters, but not being called by anything. There's no do_action('publish_post') in all of trunk.

Was this supposed to do something?

It's dynamically built... that's why you couldn't find it:

function wp_transition_post_status($new_status, $old_status, $post) {
	if ( $new_status != $old_status ) {
		do_action('transition_post_status', $new_status, $old_status, $post);
		do_action("${old_status}_to_$new_status", $post);
	}
	do_action("${new_status}_$post->post_type", $post->ID, $post);
}

This is really cool, BTW.