Re: PHP 4.0 Bug #8935 Updated: A reference to 'this' can not be used in the constructor method for a class.

Uhm..I have always closed the duplicates after the original (which they refer to) was closed. Any opinions about this? As the current bug system doesn't have any support for 'multiple' closing, I think it's better to close bugs after they are fixed, be it a duplicate or not. --Jani On 9 Mar 2001 andre@php.net wrote: >ID: 8935 >Updated by: andre >Reported By: johanp@aditus.nu >Old-Status: Closed >Status: Duplicate >Bug Type: Class/Object related >Assigned To: >Comments: > >not really this is only a duplicate report for an already >fixed bug... > >Previous Comments: >--------------------------------------------------------------------------- > >[2001-03-09 17:09:08] sniper@php.net >It's fixed -> closed. > >--Jani > > >--------------------------------------------------------------------------- > >[2001-03-09 13:50:45] andre@php.net >this has been fixed for months, >please use =& new instead of = new in this special case > >--------------------------------------------------------------------------- > >[2001-02-24 14:14:09] jmoore@php.net >Please see the 4.0.4 release change log a lot of things along this line were fixed. > >James > >--------------------------------------------------------------------------- > >[2001-01-26 09:37:16] johanp@aditus.nu >The following script demonstrates the problem. > ><?php >/* >thistest.php >jp, 2001-01-25 >Demonstration of bug in passing '$this' as a reference in the constructor. >The problem is that it will not be a reference to the newly created object that is passed but >rather a new copy. This is demonstrated below. > >The Container class is just a driver class > >The bug is demostrated in the A1 class. The A class uses an Init() method to pass the >'$this' reference which is a workaround for this particular bug. > >Analysis of problem: >It seems that the '$this' pointer is not safe to use in the constructor since it >probably doesn't get properly initialized for the object until after the constructor has been >run. > >*/ > > > >class ContainerA { > var $a; > function ContainerA() { > $this->a=new A(); > $this->a->Init(); > echo "A val before calling change: > ".$this->a->val."<br>"; > $this->a->bobj->ChangeA(); > echo "A val after calling change (should be 3): > ".$this->a->val."<br>"; > } >} > >class A { > var $val=1; > var $bobj=null; > > function A() { > $this->bobj = new B(); > } > function Init() { > // Workaround it is safe to use a refernce to this outside the constuctor > $this->bobj->Init(&$this); > } > function SetVal($v) { > $this->val=$v; > } >}; > >class B { > var $aobj=null; > function B() { > } > function Init(&$obj) { > $this->aobj=&$obj; > } > function ChangeA() { > $this->aobj->SetVal(3); > } >}; > >class ContainerA1 { > var $a; > function ContainerA1() { > $this->a=new A1(); > echo "A val before calling change: > ".$this->a->val."<br>"; > $this->a->bobj->ChangeA(); > echo "A val after calling change (should be 3): > ".$this->a->val."<br>"; > } >} > >// BUG >class A1 { > var $val=1; > var $bobj=null; > > function A1() { > $this->bobj = new B(); > > // BUG. A reference of 'this' is NOT passed here as it seems but a copy! > // Hence the bobj will contain another copy of A1 and not the one we > // are just creating. > $this->bobj->Init(&$this); > } > function SetVal($v) { > $this->val=$v; > } >}; > >echo "Demonstration of 'this' bug.<p>"; >echo "Using class A (workaround)<br>"; >$c1=new ContainerA(); > >echo "<p>Using class A1 (BUG)<br>"; >$c1=new ContainerA1(); > >?> > >--------------------------------------------------------------------------- > > > >ATTENTION! Do NOT reply to this email! >To reply, use the web interface found at >http://bugs.php.net/?id=8935&edit=2 > > >