- var_dump: documentation ( source)
- function_exists: documentation ( source)
- define: documentation ( source)
<?php
define('OK', function_exists('ok'));
var_dump( OK );
//Fatal error: Constant expression contains invalid operations in /in/tOnQh on line 7
//Process exited with code 255.
//class A{ const OK = function_exists('ok'); }
//var_dump( A::OK );