{ public $roof_type; public $num_stories; public $num_rooms; public $num_baths; public $has_pool; public function setZoning($zoning) { if (preg_match('/commercial/', $zoning)) { die("can't set commercial for a house"); } parent::setZoning($zoning); //$this->setZoning($zoning); //$this->zoning = $zoning; } public function setAskPrice($ask_price) { $this->ask_price = $ask_price; } } class Warehouse extends Property { public $sq_footage; public $kw_capacity; public $ceiling_height; } $house = new House(); $house->setAskPrice(100); $house->num_rooms = 4; $house->setZoning('residential, single family'); print_r($house);