note 124990 added to language.oop5.references

Two concise examples that illustrate the true difference between "object-assignment by value" vs "object-assignment by reference": <?php class a{ public $a = 2; } class b{ public $b = 3; } //------------ //Code Set 1 (third line down does not use ampersand(&), it is an object assignment by copy): $a = new a(); $b = new b(); $c = $a; //<--copy by value. echo $c->a . "\n"; //output: 2 $a = $b; //This assignment has no affect on $c. echo $c->a . "\n"; //output: 2 ($c is still a copy of $a, so this works) echo $c->b . "\n"; //output: "Undefined property: a::$b" ($c is still a copy of $a (not $b), so this does not work) //------------ //Code Set 2 (third line down DOES use ampersand(&), it is an object assignment by reference/pointer): $a = new a(); $b = new b(); $c = &$a; //<--copy by reference/pointer. echo $c->a . "\n"; //output: 2 $a = $b; //This assignment replaces $c's underlying object value. echo $c->a . "\n"; //output: "Undefined property: b::$a" ($c is no longer a copy of $a, so this does not work) echo $c->b . "\n"; //output: 3 ($c now points to $b, so this works) //------------ ?> ---- 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/124990 Del: integrated -- https://master.php.net/note/delete/124990/integrated Del: useless -- https://master.php.net/note/delete/124990/useless Del: bad code -- https://master.php.net/note/delete/124990/bad+code Del: spam -- https://master.php.net/note/delete/124990/spam Del: non-english -- https://master.php.net/note/delete/124990/non-english Del: in docs -- https://master.php.net/note/delete/124990/in+docs Del: other reasons-- https://master.php.net/note/delete/124990 Reject -- https://master.php.net/note/reject/124990 Search -- https://master.php.net/manage/user-notes.php