you could pass an array in construtor which will initialize its value by looping it. something like
public function __construct($param=array('db'=>'dbcredential','customer'=>'some name','event'=>'spme event')){ foreach($param as $key=>$value){ $this->$key=$value;}}
if you want that no other property be set rather than the property you initialized at first you ,can use isset() in loop before assigning the value