A Guide to the Actions API

A GUIDE TO THE ACTIONS API

WordPress thesis frameworks have been all a rave nowadays, as well as righteously so. Everybody’s possibly regulating one or rolling their own flavor. Theme frameworks deliver multiform brand new concepts to thesis authoring which compartment now, usually plugin developers have been receiving value of. In this article, I’m starting to deliver we to a actions API, as well as mangle it down so we can assimilate how it all works.If we don’t already know about movement hooks, they’re elementary small functions which movement as a placeholder to concede alternative functions to “hook” in to which sold mark where a placeholder duty was called at. Here’s an e.g. to denote that:

wp_head() an movement offshoot which is located in your theme’s header.php is a budding e.g. of how movement hooks work. wp_head is located in your theme’s header.php. Let’s take a rise at a source:

/**
 * Fire a wp_head action
 *
 * @since 1.2.0
 * @uses do_action() Calls 'wp_head' hook.
 */
function wp_head() {
	do_action('wp_head');
}

As you’ll notice, there’s zero essentially in wp_head which prints out any scripts or meta tags. wp_head simply calls a do_action duty with a initial parameter being wp_head. And that’s where a sorcery lies: do_action();

In sequence to emanate an movement hook, we simply need to emanate a placeholder duty which calls do_action(); with a initial parameter being a name of a preferred hook. Typically, you’d wish a name to be only what a duty name is, though it can be anything you’d like; as prolonged as a name isn’t already in use.

Now here’s how a sorcery works: Once we call a do_action('wp_head'); with a initial parameter being a name of a preferred hook, WordPress registers this call in to a system. With a offshoot right away purebred in to a system, we can right away call a add_action(); duty permitting us to offshoot in to wp_head.

Viewing a source of default-filters.php where WordPress hooks in to a wp_head movement offshoot reveals this:

add_action('wp_head', 'wp_enqueue_scripts', 1);
add_action('wp_head', 'feed_links_extra', 3);
add_action('wp_head', 'rsd_link');
add_action('wp_head', 'wlwmanifest_link');
add_action('wp_head', 'index_rel_link');
add_action('wp_head', 'parent_post_rel_link', 10, 0);
add_action('wp_head', 'start_post_rel_link', 10, 0);
add_action('wp_head', 'adjacent_posts_rel_link', 10, 0);
add_action('wp_head', 'locale_stylesheet');
add_action('wp_head', 'noindex', 1);
add_action('wp_head', 'wp_print_styles', 8);
add_action('wp_head', 'wp_print_head_scripts', 9);
add_action('wp_head', 'wp_generator');

More than a dozen functions get bending in to wp_head by default. You’ll notice which a initial parameter is wp_head, with a second parameter being a PHP function. What add_action does, is register those PHP functions to a wp_head movement hook. So at your convenience a do_action('wp_head'); is called, WordPress checks to see if any PHP functions have been purebred to wp_head, as well as if so, govern them. And that’s how a WordPress actions API works.

Now because go by all which difficulty when WordPress could have simply enclosed all these functions in to a tangible thesis itself? Well for one, a actions API creates your thesis destiny proof. If we beheld right on top of a wp_head function, there was a criticism saying which it was there since WordPress 1.2.0. That’s a flattering prolonged time, as well as we can assure we which all those PHP functions purebred to a wp_head offshoot weren’t there behind in those days. Using a actions API, WordPress was means to make make make make use of of of of a single placeholder duty as well as offshoot in functionality after down a line when needed, similar to feed_links_extra, which was introduced in WordPress 2.8.

Using a actions API, we can additionally mislay PHP functions purebred to a sold offshoot regulating remove_action();

remove_action( 'wp_head', 'wp_generator' );

The initial parameter indicates which offshoot we’re targeting, as well as a second is a tangible PHP duty we’d similar to to remove. This duty is utilitarian if your regulating a thesis horizon as well as would similar to to mislay a small of their default behavior.

So to recap, a actions API allows we to emanate placeholder functions in your template files, permitting alternative functions to offshoot in to which sold mark only by induction them regulating a add_action call. To review some-more on this topic, here have been a couple of links which additionally explains a matter:

The actions API is only how plugins have been means to supplement facilities as well as functionality to WordPress as those small do_action() calls have been done all via a WordPress core. Nowadays, themes have been starting to get some-more advanced, so they proposed creation make make make make use of of of of of a actions API to concede some-more coherence as well as destiny proof. In a subsequent article, I’ll denote a small beautiful uses for movement hooks which we can make make make make use of of of of in your themes.