class BB extends AA { public function say() { echo "BB..."; } } $a = new BB(); $a->say(); interface AAA { public function say(); const cProp = "hello"; } class BBB implements AAA { public function say() { echo " say in BBB..."; echo self::bCProp; } const bCProp = "world"; } $a = new BBB(); $a->say(); echo <<<'NOW' 123456789\n0 !@#$%^&*() qwertyuiopasdfghjklzxcvbnm,./ NOW ;