add a wp_notification functionality to output notices and errors on the front end

[Denis-de-Bernardy]

On occasion, a plugin needs to return some kind of feedback. It would be nice if a standard hook existed for this.

It could go something like this:

add_filter(wp_notification, foobar)

foobar() appends to an array of notification messages that get displayed to the user on the front end.

then, on page load:

• in wp_head if notifications is not empty, we add a style, wp_notification, that makes elements of this class invisible, and we load jQuery

• if do_action(wp_notification) is explicitly called on the page, we display the messages in there, without the class, and disable the notification on the wp_footer hook

• an action gets fired on wp_footer if do_action(wp_notification) is not called, and we use ajax to place the needed messages in a absolutely positioned div element, with a close button.

we could also add some kind of do_action(wp_commentform_notification), nearby the comments form, to output comment-related errors in their "correct" location as well.

[Denis-de-Bernardy]

Related: #4332, #9203

[westi]

Moving to the Template Component as this is asking for a new template tag and related functionality.

Moving to Future Release as there is no patch.

[nacin]

This is an interesting thought but as this never went anywhere, I'm closing this. I wouldn't be surprised if it gets revived later, of course. But this is no small paradigm shift.