apply_filters_ref_array( string $tag, array $args )

Execute functions hooked on a specific filter hook, specifying arguments in an array.


Description Description


Parameters Parameters

$tag

(string) (Required) The name of the filter hook.

$args

(array) (Required) The arguments supplied to the functions hooked to $tag.


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Return Return

(mixed) The filtered value after all hooked functions are applied to it.


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Source Source

File: wp-includes/plugin.php

function apply_filters_ref_array($tag, $args) {
	global $wp_filter, $wp_current_filter;

	// Do 'all' actions first
	if ( isset($wp_filter['all']) ) {
		$wp_current_filter[] = $tag;
		$all_args = func_get_args();
		_wp_call_all_hook($all_args);
	}

	if ( !isset($wp_filter[$tag]) ) {
		if ( isset($wp_filter['all']) )
			array_pop($wp_current_filter);
		return $args[0];
	}

	if ( !isset($wp_filter['all']) )
		$wp_current_filter[] = $tag;

	$filtered = $wp_filter[ $tag ]->apply_filters( $args[0], $args );

	array_pop( $wp_current_filter );

	return $filtered;
}

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Changelog Changelog

Changelog
Version Description
3.0.0 Introduced.


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User Contributed Notes User Contributed Notes

  1. Skip to note content
    Contributed by Codex

    As of PHP 5.4, the array is no longer passed by reference

    Before PHP 5.4, your callback is passed a reference pointer to the array. Your callback can use this pointer to access all the array elements. Adding a filter and declaring a call back that hooks the above example filter could look like this:

    function wpdocs_my_callback( $args ) {
        // Access values with $args[0], $args[1] etc.
    }
    add_filter( 'my_filter', 'wpdocs_my_callback' );
    

    Because the array was passed by reference, any changes to the array elements are applied to the original array outside of the function’s scope.

    Regardless of PHP version, you can specify the number of array elements when adding the filter, and receive each element in a separate parameter in the callback function declaration like so:

    function wpdocs_my_callback( $arg1, $arg2, $arg3, $arg4 ) {
        // Access values with $args1, $args2 etc.
    }
    add_action( 'my_filter', 'wpdocs_my_callback', 10, 4 );
    

    This method copies the array elements into the parameter variables. Any changes to the parameter variables do not affect the original array.

    As of PHP 5.4, the array is no longer passed by reference despite the function’s name. You cannot even use the reference sign ‘&’ because call time pass by reference now throws an error. What you can do is pass the reference pointer as an array element. Doing so does require all callbacks added to the filter to expect a reference pointer. This is not something you will see in WordPress actions. This technique is provided for informational purposes only.

    apply_filters_ref_array( 'my_filter', array( &$args ) );
    
    function wpdocs_my_callback( &$args ) {
        //access values with $args[0], $args[1] etc.
    }
    add_action('my_filter', 'wpdocs_my_callback');
    

    Because the original array was passed by reference, any changes to the array elements are applied to the original array outside of the function’s scope.

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