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Date: Thu, 19 Aug 2010 18:10:11 +0300
To: Stas Malyshev <smalyshev@sugarcrm.com>
Cc: PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] inheritance check too strict?
From: zeev@zend.com (Zeev Suraski)

At 10:51 19/08/2010, Stas Malyshev wrote:
>Hi!
>
>I recently noticed this code:
>
><?php
>error_reporting(E_ALL | E_STRICT);
>
>class ObjParent {
>         public function set($param2 = ''){ }
>}
>
>class ObjChild extends ObjParent {
>         public function set(){ }
>}
>
>produces a E_STRICT warning. I don't really see a point in it - 
>there's no problem whatsoever with child function ignoring some 
>arguments from parent call. Anybody could explain why this check is there?

As others noted I also think that this warning is correct.  Code that 
deals with ObjParent objects is allowed to call to set() with a 
parameter.  It's also supposed to be able to treat ObjChild objects 
transparently, because they're specialized of ObjParent.  If this 
function signature was allowed - it can end up calling 
ObjChild::set() with an argument - which ObjChild() doesn't support.

The other way around - making ObjChild::set() more support more 
signatures than the signature it's 'overriding' - makes perfect sense 
and is allowed.

Regarding the other issue that was raised here, I didn't recall we 
made is_a() checks on class type hints during signature validation, 
but if we do - it should be done using the same rules - a child 
class's signature must be at least as lax as it's parent - or more.

Zeev