Need get_filters() to push-and-pop current filter settings

  • Resolved wlindley

    (@wlindley)


    12 years, 3 months ago

    I have a plugin which uses filters to handle what-to-output.

    Now I am writing a widget that will call the plugin directly, but would like to override the filters on a per-widget-instance basis. That means I need to “push” or save my plugin’s filters, set them, call the plugin, and “pop”/restore the filter settings.

    Unfortunately altho wordpress has a has_filter() to see whether a specific function is hooked to a filter, the user’s theme or other plugins could have set the filters to be anything.

    I studied plugin.php and discovered WP has no get_filters() to retrieve the entire current list of functions assigned to a filter. There really should be a get_filters($tag) and a get_actions($tag) which basically return what is currently WP’s internal array.

    I would prefer not to hack WP’s internal variables but see no alternative at this point. Any ideas?

Viewing 3 replies - 1 through 3 (of 3 total)
  • Moderator bcworkz

    (@bcworkz)

    Since you know the function names of your own filter, you can use remove_filter() and remove_action() to take your own plugin out of action, then use add_filter() and add_action() to restore afterwards.

    You’re not really supposed to need to be concerned about other hooks into a particular filter or action, thus the lack of a listing function. Of course, things don’t always work out so well, and it would be good to know.

    Thread Starter wlindley

    (@wlindley)

    Except that, other people’s themes are supposed to override the defaults that I created, and put their own filter-sets in. If a widget comes along and clobbers that, all the other invocations of the plugin will be broken… that is why I need to save the filter state and politely restore it.

    Thread Starter wlindley

    (@wlindley)

    To answer my own question, here are two rather unfortunately hacked subroutines that will return the entire current state of a filter, and reset a filter to such a saved state.

    function get_filter($tag) {
  # Returns the current state of the given WordPress filter.
  global $wp_filter;
  return $wp_filter[$tag];
}

    and then

    function set_filter($tag, $saved) {
  # Sets the given WordPress filter to a state saved by get_filter.
  remove_all_filters($tag);
  foreach ($saved as $priority => $func_list) {
    foreach ($func_list as $func_name => $func_args) {
      add_filter($tag,$func_args['function'], $priority, $func_args['accepted_args']);
    }
  }
}

    Example usage:

    $was_filter = get_filter('autonav_create_list_item');
# Erase filters
remove_all_filters('autonav_create_list_item');
# .... do something clever with the filter
# and now restore it to the user's settings
set_filter('autonav_create_list_item', $was_filter );
Viewing 3 replies - 1 through 3 (of 3 total)
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