oop - PHP Have Object Return Different Object -

in few different places call:

$model=new makecall($form); 

i have updated makecall class several changes want take affect after given date. renamed original class makecallold

how can leave calls to:

$model=new makecall($form); 

intact , within makecall this:

class makecall { ...      public function __construct($form)     {         //use legacy makecallold stuff before 2016-10-01         if ($form['date']<'2016-10-01') {             $object=new makecallold($form);             return $object;         }          $this->perform several functions , set variables... 

this returns empty object of class makecallold not appear run constructor in makecallold properties empty. entire object of makecallold dropped $model.

what need static factory constructor. way should doing add initialization logic or switch constructors depending on argument.

class makecall {      public function __construct($form)     {         $this->form = $form;     }      public function showform(){         echo $this->form;     }       public static function create($form){         //put logic picking object or whatever here!         $object = new makecall($form);         //do more initializing if want here!         return $object;      } }  $form = "asdasd"; $model= makecall::create($form); $model->showform();