Does a theme really need to hook after_setup_theme in functions.php?

Hi @joyously…thanks for your help. Much appreciated 🙂

I appreciate that everyone believes this practice adds value but no one explains why that is the case for a theme. The plugins and child theme load before the theme and can hook after_setup_theme so they can make adjustments before and after the theme loads whether the theme hooks after_setup_theme or not.

So the loading sequence is:

plugins / child theme / theme /

and the theme hook sequence is:

setup_theme / theme processing / after_setup_theme

So you can see that in a sequential processing model there is no after_setup_theme hook value for a theme. There is after_setup_theme hook value for plug-ins and child themes who want to override the theme but there is no value I can see for a theme to hook after_setup_theme.

Can you think of a use-case that requires the theme to hook after_setup_theme?

Thanks in advance.

Hi @joyously. Thanks for that.

Can you clarify your last sentence for me please

And if the theme doesn’t use the hook, the child theme and plugins can’t remove the theme code

.

The child theme and the plugins can always hook after_theme_setup and override anything the theme makes overridable whether the theme uses after_setup_theme or not. As I stated previously the theme loading-process is sequential and all a theme really does is load resources, hooks and filters. Anything that can be overridden…can be overridden whether the theme hooks after_setup_theme or not.

I’ll give you an example…add_theme_support( 'post-thumbnails' );

If a plug-in or child-theme wants to override the theme and disable post-thumbnails for some reason then they hook after_setup_theme with a function that calls remove_theme_support( 'post-thumbnails' ); It wouldn’t matter whether the theme invoked add_theme_support( ‘post-thumbnails’ ) in functions.php or a function hooked to after_setup_theme;

Could you please give me a counter-case…something that can’t be done by a plug-in / child-theme if the theme does-not hook after_theme_setup. I’m not being disingenuous…I can’t find any technical reason for a theme to hook after_theme_setup. The purpose of this post is to double-check find a counter-case if my assumption is faulty.

Thanks again for your thoughts. Much appreciated.

Hi @joyously. Thanks for your patience I think we are close to a meeting of minds 🙂

Your point about

If the child theme or plugin wanted to undo the parent theme’s code, wouldn’t it be most future-proof and easier to unhook after_setup_theme than to address each thing individually, not knowing when the theme would update and add something new?

is an interesting question. It is unlikely that a plug-in or child theme would unhook the entire theme callback function because, at present, there is no standardisation in what is included in the theme callback function hooked to after_setup_theme by various themes. For example it would be unlikely that a child theme or plugin would bulk discard the following theme callback function hooked to after_setup_theme (there would be very little left of the theme!):

	private function load_theme_supports() {
		add_theme_support( 'load_theme_admin_menus' );
		add_theme_support( 'widgets' );
		add_theme_support( 'post-thumbnails' );
		add_theme_support( 'automatic-feed-links' );
		add_theme_support( 'align-wide' );
		add_theme_support( 'wp-block-styles' );
		add_theme_support( 'responsive-embeds' );
		add_theme_support( 'post-formats' );
		add_theme_support( 'html5' );
		add_theme_support( 'custom-logo' );
		add_theme_support( 'custom-header-uploads' );
		add_theme_support( 'custom-header' );
		add_theme_support( 'title-tag' );
		add_theme_support( 'custom-background' );
		add_theme_support( 'starter-content' );
	}

But I agree with you this would be useful IF the WP core group standardised on what a theme puts in its after_setup_theme callback function.

The other aspect of your idea is the “bulk discard” as a future-proofing capability…that’s a can of worms though since each hookable callback function operates in a context (core or theme) so there is a limit to what is reasonably hookable before it becomes impossible for an extended theme to become unsupportable in the field due to the numerous parties and permutations. Having said that, the after_setup_theme hooked callback function is a reasonable place to load specific optional theme feature packages.

Your point about

And regardless of the order of execution (which is one of my points of argument you ignore), it’s the WordPress way to use actions and filters, so that the order can be rearranged without needing to change all the code

is a reasonable one…actions / filters is the WordPress way…but only when needed. I cannot imagine a world where the after_setup_theme does NOT happen immediately after the theme completes its setup. So although the after_setup_theme is of use to plugins and child-themes, it is not necessary for the theme to use it for the plugins and themes to override before or after.

Summary at this point in our discussion:

A) It would be useful if there was a core standard for what themes put in an after_setup_theme callback function.

B) after_setup_theme hooked callback function may be a useful mechanism to modularise optional theme feature packages with the express purpose of being bulk replaced (unhook) or selectively customised (contained functions can be overridden or augmented through hooks an filters).

Thanks again for your input. It has been most helpful and much appreciated 🙂

Thanks again @joyously .

I appreciate your experience and that you have been patiently trying to get a across some points that for some reason my brain is not recognising. My summary was an attempt to restate in my own words what I thought you were trying to say. Obviously I missed the mark. Sorry for that.

Let me try again to restate what I think you are trying to get across (and again…feel free to correct me)…

A modularised alternative to a theme’s functions.php is superior to a monolithic theme’s functions.php in that it allows interleaved customisation. after_setup_themeis a useful standard hook for those theme modules to be attached to.

Better?

It is interesting to note though that what I see in most themes is that their after_setup_theme hooked callback functions just include the standard add_theme_support(‘abc’); statements I listed above which can all be overridden whether in a after_setup_theme hooked callback function or in the functions.php.
That’s part of the reason I opened this post. To get other views like yours on what should be in the functions.php and what should be in one or more after_setup_theme hooked callback functions.

It sounds like your preferred theme design involves some code in the functions.php, and some in two after_setup_theme hooked callback functions.

Any wisdom as to what code makes sense to leave in functions.php and what to modularise in the after_setup_theme hooked callback functions?

Cheers 🙂

Thanks @joyously . You’ve helped me to gain a broader perspective of the options. Much appreciated 🙂