note 124995 added to language.oop5.references

Concise reminders of the behaviors of object assignments, with and without using the "&" operator... <?php class clsA{ public $propA = 2; } class clsB{ public $propB = 3; } //------------ $a = new clsA(); $c = $a; //Both of these vars now refer to the same object-instance (an assignment-by-reference). $c->propA = 22; //Use one of the vars to change the instance's property. echo $c->propA . "\n"; //output: 22 echo $a->propA . "\n"; //output: 22 //------------ $b = new clsB(); $a = $b; //Before this assignment, both $c and $a referred to the same object instance; this is no longer the case after $a is switched to reference the instance of clsB. echo $c->propA . "\n"; //output: 22 (this works because $c is still a reference to the object instance of type clsA) echo $c->propB . "\n"; //output: "Undefined property: clsA::$propB" (did not work because $c is not a reference to the object instance of type clsB) //------------ //Start over and use the "&" operator... $a = new clsA(); $b = new clsB(); $c = &$a; //<--$c will refer to whatever $a currently and "futuristically" refers to (also a type of assignment-by-reference); in C-language, you would think of this as copying a pointer. echo $c->propA . "\n"; //output: 2 $a = $b; //This assignment causes $c to refer to a new/different object. echo $c->propA . "\n"; //output: "Undefined property: clsB::$propA" (does not work since $c no longer refers to the object instance of type clsA) echo $c->propB . "\n"; //output: 3 (works since $c now refers to the object instance of type clsB) //------------ ?> ---- Server IP: 45.112.84.4 Probable Submitter: 38.142.137.34 (proxied: 96.61.135.240) ---- Manual Page -- http://php.net/manual/en/language.oop5.references.php Edit -- https://master.php.net/note/edit/124995 Del: integrated -- https://master.php.net/note/delete/124995/integrated Del: useless -- https://master.php.net/note/delete/124995/useless Del: bad code -- https://master.php.net/note/delete/124995/bad+code Del: spam -- https://master.php.net/note/delete/124995/spam Del: non-english -- https://master.php.net/note/delete/124995/non-english Del: in docs -- https://master.php.net/note/delete/124995/in+docs Del: other reasons-- https://master.php.net/note/delete/124995 Reject -- https://master.php.net/note/reject/124995 Search -- https://master.php.net/manage/user-notes.php