php - How does Laravel MessageBag work? -

i encountered magical laravel (4.2), want explaind how possible.

when messagebag class in class a

and pass variable class b, somehow class b overrides class messagebag without me declaring it.

class classa {      public function test()     {         $msgbag = new \illuminate\support\messagebag;          new classb($msgbag);          if($msgbag->any()) {             #this trigger , spit out "message class b"             dd($msgbag);         }else{             print('nope no messages');         }     } }  class classb {      protected $msgbag;      function __construct(\illuminate\support\messagebag $msgbag)     {         $this->msgbag = $msgbag;         $this->setmessage();     }      public function setmessage()     {         $this->msgbag->add('message', 'message class b');     } } 

i tested same thing normal object behaved expected to.

class classa {      public function test()     {         $object = (object) ['class'=>'a'];          new classb($object);          dd($object->class); # return     } }  class classb {      protected $object;      function __construct($object)     {         $this->object = $object;         $this->setmessage();     }      public function setmessage()     {         $this->object = (object) ['class'=>'b'];     } } 

so laravel doing behind seances make possible, haven't found yet.

does know how replicate ?

there no laravel magic here. in php, objects behave though passed reference (although technically not, that's not relevant here).

this means in first example, messagebag object created same object as 1 assigned $this->msgbag in classb. therefore, modifications made object inside classb going seen when inspect $msgbag object in test() method in classa.

this not case in second example, because in setmessage() method, override first object entirely new one.

basically behaving expect normal php.