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_wp_filter_build_unique_id()

_wp_filter_build_unique_id( string $hook_name, callable|string|array $callback, int $priority ): string

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This function’s access is marked private. This means it is not intended for use by plugin or theme developers, only in other core functions. It is listed here for completeness.

Builds a unique string ID for a hook callback function.

Description

Functions and static method callbacks are just returned as strings and shouldn’t have any speed penalty.

Parameters

$hook_namestringrequired
Unused. The name of the filter to build ID for.
$callbackcallable|string|arrayrequired
The callback to generate ID for. The callback may or may not exist.
$priorityintrequired
Unused. The order in which the functions associated with a particular action are executed.

Return

string Unique function ID for usage as array key.

Source

function _wp_filter_build_unique_id( $hook_name, $callback, $priority ) {
	if ( is_string( $callback ) ) {
		return $callback;
	}

	if ( is_object( $callback ) ) {
		// Closures are currently implemented as objects.
		$callback = array( $callback, '' );
	} else {
		$callback = (array) $callback;
	}

	if ( is_object( $callback[0] ) ) {
		// Object class calling.
		return spl_object_hash( $callback[0] ) . $callback[1];
	} elseif ( is_string( $callback[0] ) ) {
		// Static calling.
		return $callback[0] . '::' . $callback[1];
	}
}

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Used byDescription
WP_Hook::add_filter()wp-includes/class-wp-hook.php

Adds a callback function to a filter hook.

WP_Hook::remove_filter()wp-includes/class-wp-hook.php

Removes a callback function from a filter hook.

WP_Hook::has_filter()wp-includes/class-wp-hook.php

Checks if a specific callback has been registered for this hook.

Changelog

VersionDescription
5.3.0Removed workarounds for spl_object_hash().
$hook_name and $priority are no longer used, and the function always returns a string.
2.2.3Introduced.

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