SWDB/application/helper/APPLICATION_Helper.php

<?php
    /**
     * App helper file.
     *
     * Provides a helper to perform app related operations.
     *
     * @category Helper.
     */

    /**
     * Require dependent files if not present.
     */
    require_once(PATH::HELPER . "Helper.php");

    /**
     * Application helper.
     *
     * Contains app-related utilities.
     *
     * @category Helper.
     */
    final class APPLICATION extends Helper{

        /**
         * Checks if a value is a valid one in a constant class.
         *
         * It will intentionally fail when used for a non constant class.
         *
         * @param string $class Name of the class.
         * @param int $value Value to check.
         * @return bool True if the value is defined, false otherwise.
         */
        public static function valid_id($class, $value){
            if (strtoupper($class) != $class){
                return false;
            }
            if (!class_exists($class, false)){
                return false;
            }
            $reflect = new ReflectionClass($class);
            if (in_array($value, $reflect->getConstants())){
                return true;
            }
            else{
                return false;
            }
        }
    }
?>