<?php # Example #4 Interfaces with constants interface a { const b = 'Interface constant'; } // Prints: Interface constant echo a::b . "\n"; // This will however not work because it's not allowed to // override constants. class b implements a { const g = 'Class constant'; // if trying to override a constant in implemented class // Interface constantPHP Fatal error: Cannot inherit previously-inherited or override constant b from interface a in /media/linux-on/certification/php5.5zendcertification/more/phpcert/classesobjs/class-interface-4.php on line 16 public function getConstant() { echo a::b . ' in getConstant 22 ' . "\n"; } } echo a::b . "\n"; echo b::g . "\n"; echo b::b . "\n"; $oB = new b(); $oB->getConstant();