do_action

Execute functions hooked on a specific action hook.

Description

do_action( (string) $tag, (string) $arg = '' ); 

This function invokes all functions attached to action hook $tag.. It is possible to create new action hooks by simply calling this function, specifying the name of the new hook using the $tag. parameter.

You can pass extra arguments to the hooks, much like you can with apply_filters(…).

Parameters (2)

0. $tag (string)
The name of the action to be executed.
1. $arg — Optional. (string) => ''
Additional arguments which are passed on to the functions hooked to the action. Default empty.

Usage

  1. if ( !function_exists( 'do_action' ) ) { 
  2.     require_once ABSPATH . WPINC . '/plugin.php'; 
  3. } 
  4.   
  5. // The name of the action to be executed. 
  6. $tag = ''; 
  7.   
  8. // Optional. Additional arguments which are passed on to the 
  9. // functions hooked to the action. Default empty. 
  10. $arg = ''; 
  11.   
  12. // NOTICE! Understand what this does before running. 
  13. $result = do_action($tag, $arg); 
  14.     

Defined (1)

The function is defined in the following location(s).

/wp-includes/plugin.php  
  1. function do_action($tag, $arg = '') { 
  2.     global $wp_filter, $wp_actions, $wp_current_filter; 
  3.  
  4.     if ( ! isset($wp_actions[$tag]) ) 
  5.         $wp_actions[$tag] = 1; 
  6.     else 
  7.         ++$wp_actions[$tag]; 
  8.  
  9.     // Do 'all' actions first 
  10.     if ( isset($wp_filter['all']) ) { 
  11.         $wp_current_filter[] = $tag; 
  12.         $all_args = func_get_args(); 
  13.         _wp_call_all_hook($all_args); 
  14.     } 
  15.  
  16.     if ( !isset($wp_filter[$tag]) ) { 
  17.         if ( isset($wp_filter['all']) ) 
  18.             array_pop($wp_current_filter); 
  19.         return; 
  20.     } 
  21.  
  22.     if ( !isset($wp_filter['all']) ) 
  23.         $wp_current_filter[] = $tag; 
  24.  
  25.     $args = array(); 
  26.     if ( is_array($arg) && 1 == count($arg) && isset($arg[0]) && is_object($arg[0]) ) // array(&$this) 
  27.         $args[] =& $arg[0]; 
  28.     else 
  29.         $args[] = $arg; 
  30.     for ( $a = 2, $num = func_num_args(); $a < $num; $a++ ) 
  31.         $args[] = func_get_arg($a); 
  32.  
  33.     $wp_filter[ $tag ]->do_action( $args ); 
  34.  
  35.     array_pop($wp_current_filter); 
  36. }