Remove Actions/Filters added via Anonymous Functions

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The problem is that you can’t distinguish form an anonymous function and another, so yes, it is possible to remove a closure (i.e. anonymous function) but if more than one closure act on same filter at same priority you have to make a choice, remove them all, ore remove only one (without knowing exactly which).

I’ll show how to remove them all using a function highly derived from the one in the @toscho answer you posted:

/**
 * Remove an object filter.
 *
 * @param  string $tag                Hook name.
 * @param  string $class              Class name. Use 'Closure' for anonymous functions.
 * @param  string|void $method        Method name. Leave empty for anonymous functions.
 * @param  string|int|void $priority  Priority
 * @return void
 */
function remove_object_filter( $tag, $class, $method = NULL, $priority = NULL ) {
  $filters = $GLOBALS['wp_filter'][ $tag ];
  if ( empty ( $filters ) ) {
    return;
  }
  foreach ( $filters as $p => $filter ) {
    if ( ! is_null($priority) && ( (int) $priority !== (int) $p ) ) continue;
    $remove = FALSE;
    foreach ( $filter as $identifier => $function ) {
      $function = $function['function'];
      if (
        is_array( $function )
        && (
          is_a( $function[0], $class )
          || ( is_array( $function ) && $function[0] === $class )
        )
      ) {
        $remove = ( $method && ( $method === $function[1] ) );
      } elseif ( $function instanceof Closure && $class === 'Closure' ) {
        $remove = TRUE;
      }
      if ( $remove ) {
        unset( $GLOBALS['wp_filter'][$tag][$p][$identifier] );
      }
    }
  }
}

I’ve renamed the function remove_object_filter because it can remove all types of object filters: static class methods, dynamic object methods and closures.

The $priority argument is optional, but when removing closures it should be always used, otherwise the function will remove any closure added to the filter, no matter at which priority, because when $priority is omitted, all the filters using the target class/method or closure are removed.

How to use

// remove a static method
remove_object_filter( 'a_filter_hook', 'AClass', 'a_static_method', 10 );

// remove a dynamic method
remove_object_filter( 'a_filter_hook', 'AClass', 'a_dynamic_method', 10 );

// remove a closure
remove_object_filter( 'a_filter_hook', 'Closure', NULL, 10 );

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