id,summary,reporter,owner,description,type,status,priority,milestone,component,version,severity,resolution,keywords,cc
19986,Issue with add_filter() and add_action() when using anonymous functions.,pagesimplify,,"Referencing File: /wp-includes/plugin.php :: function add_filter()
{{{
function add_filter($tag, $function_to_add, $priority = 10, $accepted_args = 1) {
	global $wp_filter, $merged_filters;

	$idx = _wp_filter_build_unique_id($tag, $function_to_add, $priority);
	$wp_filter[$tag][$priority][$idx] = array('function' => $function_to_add, 'accepted_args' => $accepted_args);
	unset( $merged_filters[ $tag ] );
	return true;
}
}}}

When registering a function with add_filter() and add_action(), a unique id ($idx) is generated to be used as an array key in:

{{{
$wp_filter[$tag][$priority][$idx]
}}}

The function that creates this unique key ($idx) returns the function name passed into the $function_to_add parameter.
{{{
$idx = _wp_filter_build_unique_id($tag, $function_to_add, $priority);
}}}

If the $function_to_add parameter is a string, the function _wp_filter_build_unique_id() returns the original function name.

{{{
function _wp_filter_build_unique_id($tag, $function, $priority) {
	global $wp_filter;
	static $filter_id_count = 0;

	if ( is_string($function) )
		return $function;
   ...
}
}}}

Returning a string value for the unique id is a problem when the function is an anonymous function generated using create_function(). The reason is anonymous functions are named as ""special character + lambda_XX"" or as ""ºlambda_XX"" where the first character cannot be displayed.

See attached file: anonymous_function_name.jpg

Since array keys can only be integers or strings, the following array is invalid and causes inconsistent behaviors.

{{{
$wp_filter[$tag][$priority]['ºlambda_XX']
}}}

Although I've seen instances where this will still work, I've also observed strange issues with inconsistent results where plugins should work and sometimes do not. One example is with Otto's Simple Facebook Connect plugin.  

See file: sfc-widgets.php
{{{
add_action('widgets_init', create_function('', 'return register_widget(""SFC_Fan_Box_Widget"");'));
}}}

I have not been able to isolate the conditions that allow this to work in one WordPress installation and not in others. However, I have been able to apply a patch to my installation with consistent and successful results.

See attached patch: plugin.php.diff

While this is an obscure and possibly very isolated issue, it could resolve unexplained issues related to using anonymous functions with add_filter() elsewhere.",defect (bug),new,normal,Awaiting Review,Plugins,3.3.1,minor,,has-patch,pagesimplify kpayne@…