List all hooked functions

10. List All Hooked Functions

The problem.
When things go wrong, listing all hooked functions can be very useful for debugging.

The solution.
As with the others, this code has to be pasted in your functions.php file. When you have finished debugging, don’t forget to remove the code from functions.php, or else the debugging message will continue to appear.

function list_hooked_functions($tag=false){
global $wp_filter;
if ($tag) {
$hook[$tag]=$wp_filter[$tag];
if (!is_array($hook[$tag])) {
trigger_error(“Nothing found for ‘$tag’ hook”, E_USER_WARNING);
return;
}
}
else {
$hook=$wp_filter;
ksort($hook);
}
echo ‘<pre>';
foreach($hook as $tag => $priority){
echo “<br />&gt;&gt;&gt;&gt;&gt;\t<strong>$tag</strong><br />”;
ksort($priority);
foreach($priority as $priority => $function){
echo $priority;
foreach($function as $name => $properties) echo “\t$name<br />”;
}
}
echo ‘</pre>';
return;
}
Once that’s done, simply call the list_hooked_functions() function, as shown below, to print all hooked WordPress functions on your screen.

1
list_hooked_functions();
Code explanation.
If no hook name is provided to the function as an argument, then hooks are printed to the screen using the global variable $wp_filter. Alternatively, you can list one particular hook by passing its name as an attribute:

list_hooked_functions(‘wp_head’);