#38011 [Opn->Bgs]: colder
| From: | colder@php.net | Date: | Wed, 05 Jul 2006 16:01:39 +0000 |
| Subject: | #38011 [Opn->Bgs]: colder | ||
| References: | 1 | Groups: | php.doc |
| Request: | Send a blank email to phpdoc+get-969373458@lists.php.net to get a copy of this message | ||
ID: 38011
Updated by: colder@php.net
-Summary: suggest $foo = &new Bar(); for PHP4
Reported By: joliver at gmx dot at
-Status: Open
+Status: Bogus
Bug Type: Documentation problem
Operating System: all
PHP Version: Irrelevant
New Comment:
There is already an explanation in the section about references:
http://php.net/language.references.whatdo
Previous Comments:
------------------------------------------------------------------------
[2006-07-05 01:18:54] joliver at gmx dot at
Description:
------------
Please provide an advice to PHP4 users to use
$foo = &new Bar();
instead of $foo = new Bar();
Contrary to the examples in the documentation, in PHP4
instances of objects should be initialisised with
$foo = &new Bar();
because here $foo is a reference to the created instance
of Bar, while for
$foo = new Bar();
$foo is a copy(!) of the instance.
Appart from performance and memory issues, in the second
case parameters in the constructors will be copied to,
because the whole object is copied. That means for
example, that for:
$foo = new Bar($this)
$foo is an instance of Bar where $this is not the owner of
that instance any more, because $foo is a copy of the
newly created instance.
Good example in german:
http://www.usegroup.de/software/phptutorial/klassen_und_objekte.html#ref_owner
Reproduce code:
---------------
<?php
class myC1
{
var
$greeting;
var $theC2;
function sayHello()
{
echo $this->greeting;
}
function myC1()
{
$this->greeting="Howdy";
$this->theC2=new myC2($this);
}
}
class myC2
{
var $owner;
function myC2(&$owner)
{
$this->owner=&$owner;
$this->owner->greeting="bah";
}
function something()
{
$this->owner->greeting="hulla";
// This is supposed to change myC1's greeting to hulla, overwriting
"bah".
}
}
$test=new myC1(); //$test=&new myC1();
$test->theC2->something();
$test->sayHello();
?>
Expected result:
----------------
$test=&new myC1();
returns the excepted result in PHP4. Please provide that
advice for PHP4 users in the documentation.
Actual result:
--------------
As described above, $test=new myC1(); returns a copy of
the instance, therefore $this in myC1 gets lost.
An advice for PHP4 users would be helpful, in my opinion
in PHP4
$foo=&new Bar(); should be used instead of
$foo=new Bar(;), which is not mentioned anywhere in the
documentation.
(of course i know in PHP5 this as been fixed because
objects are passed by reference.)
Thank you!
Oliver
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/?id=38011&edit=1