WP_Error class for returning errors

[ryan]

I'd like a nicer way to return errors, especially when validating forms and returning multiple error messages. Let's have a WP_Error class that holds error codes and messages. An is_wp_error function checks return values to see if they are a WP_Error.

function doer_of_stuff() {
  return  new WP_Error('broke', __("I've fallen and can't get up"));
}

$return = doer_of_stuff();
if ( is_wp_error($return) )
   echo $return->get_error_message();

WP_Error and is_wp_error()

(In [3667]) WP_Error. fixes #2600