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To: Marcus =?iso-8859-15?q?B=F6rger?= <helly@php.net>
Date: Wed, 16 Jul 2003 12:00:43 +0200
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References: <3F147B5D.5070406@chiaraquartet.net> <200307160127.52308.msopacua@php.net> <1422804488.20030716100114@post.rwth-aachen.de>
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Message-ID: <200307161200.43568.msopacua@php.net>
Subject: Re: [PHP-DEV] $this assignment and call_user_func question
From: msopacua@php.net (Melvyn Sopacua)

Hi again,

On Wednesday 16 July 2003 10:01, Marcus B=F6rger wrote:
[ ... ]

> MS> I'm not farmiliar with the example Greg is getting at, but the
> following bit MS> me recently:
> MS> class DomFromString extends DomDocument
> MS> {
> MS>         function DomFromString($string)
> MS>         {
> MS>                 $this =3D domxml_open_mem($string);
> MS>         }
> This should be a factory patter...static function ...return domxml_open...

Which returns a domxml object, without method 'foo'.

> MS> Note that the goal here, is to extend a class of which may not have t=
he
> source MS> (or the time/ability to modify it)  AND override it's
> constructor or the MS> constructor is provided by a function, rather than
> 'new' principle.
>
>
> You can of course overwrite the constructor in a derived class and all.

How would you know how to write the parents' constructor, if it's opaque?
If the constructor creates a resource, how would you mimmick this in PHP?

> So
> you are missing the possibility to exchange the contants of a dom clas,
> that's all you do this tricky stuff for?

The dom class is an example, but let's not focus on dom here. It does=20
illustrate the problem however, because the constructor for a string based=
=20
DomDocument is the PHP_FUNCTION(xmldoc).

Which means, the following does not work:
class DomFromString extends DomDocument
{
	function foo()
	{
		echo('foo');
	}
}

$dom =3D new DomFromString($xml);
var_dump($dom);

This is because there are three *function* constructors, which do something=
=20
usefull, which are returning the same object. I really don't see a way, to=
=20
extend this object. The primary reason is: BC, missing methods, adding=20
convenience methods.

Since PHP5 should also give a boost to PECL, I think there should be a way =
to=20
extend a C-based class, somehow. I really don't favor the $this assignment =
as=20
well, but what other option is there? Or is this specifick for the way the=
=20
domxml module is setup, and people shouldn't write their classes like that?

=2D-
Melvyn