In reply to VGR_experts_exchange at edainworks dot com
To check if a constant is boolean, use this instead:
<?php
if (TRACE === true) {}
?>
Much quicker and cleaner than using defined() and constant() to check for a simple boolean.
IMO, using ($var === true) or ($var === false) instead of ($var) or (!$var) is the best way to check for booleans no matter what. Leaves no chance of ambiguity.