Wordpress - How to know what functions are hooked to an action/filter?
Look into the global variable $wp_filter
. See my plugin for a list of all comment filters for an example:
<?php
/*
Plugin Name: List Comment Filters
Description: List all comment filters on wp_footer
Version: 1.1
Author: Fuxia Scholz
License: GPL v2
*/
add_action( 'wp_footer', 'list_comment_filters' );
function list_comment_filters()
{
global $wp_filter;
$comment_filters = array ();
$h1 = '<h1>Current Comment Filters</h1>';
$out = '';
$toc = '<ul>';
foreach ( $wp_filter as $key => $val )
{
if ( FALSE !== strpos( $key, 'comment' ) )
{
$comment_filters[$key][] = var_export( $val, TRUE );
}
}
foreach ( $comment_filters as $name => $arr_vals )
{
$out .= "<h2 id=$name>$name</h2><pre>" . implode( "\n\n", $arr_vals ) . '</pre>';
$toc .= "<li><a href='#$name'>$name</a></li>";
}
print "$h1$toc</ul>$out";
}
Sample output for pre_comment_author_email
:
array (
10 =>
array (
'trim' =>
array (
'function' => 'trim',
'accepted_args' => 1,
),
'sanitize_email' =>
array (
'function' => 'sanitize_email',
'accepted_args' => 1,
),
'wp_filter_kses' =>
array (
'function' => 'wp_filter_kses',
'accepted_args' => 1,
),
),
)
to see list of functions or actions hooked to a particular action hook you can use the following code.
global $wp_filter;
echo '<pre>';
var_dump( $wp_filter['wp_head'] );
echo '</pre>';
For debug-purposes a simple
global $wp_filter;
echo "<pre>" . print_r($wp_filter, true) . "</pre>";
would do it ...