Sprawdzenie czy interfejs nie istnieje (gdy zadeklarowany w innej wtyczce).

classes/wpdesk/interface-plugin-factory.php

@@ -4,9 +4,12 @@ if ( ! defined( 'ABSPATH' ) ) {
 	exit;
 } // Exit if accessed directly
 
+if ( !interface_exists( 'WPDesk_Plugin_Factory_1_10' ) ) {
 	interface WPDesk_Plugin_Factory_1_10 {
 		const WPDESK_FILTER_PLUGIN_CLASS = 'wpdesk_plugin_class';
 
 		static function build_plugin();
+
 		static function get_plugin_instance();
 	}
+}
\ No newline at end of file