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Date: Thu, 19 Aug 2010 20:33:19 +0100
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To: Zeev Suraski <zeev@zend.com>
CC: "Ionut G. Stan" <ionut.g.stan@gmail.com>, internals@lists.php.net, 
 smalyshev@sugarcrm.com, Dave Ingram <dave@dmi.me.uk>
References: <4C6CE273.2070501@sugarcrm.com> <4C6CE604.1010209@dmi.me.uk> <4C6CE793.1020601@sugarcrm.com> <1282206735.2561.11.camel@guybrush> <4C6CF898.5060706@gmail.com> <4C6D2EB8.30700@gmail.com> <4C6D39EA.4000705@gmail.com> <7.0.1.0.2.20100819181013.18df1df8@zend.com>
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Subject: Re: [PHP-DEV] inheritance check too strict?
From: nrixham@gmail.com (Nathan Rixham)

Zeev Suraski wrote:
> At 17:04 19/08/2010, Ionut G. Stan wrote:
>>
>> I can't call Child::foo() with an instance of Taz, but I can call 
>> Parent::foo() with such an instance. So, I can't use instances of 
>> Child wherever instances of Parent would be accepted.
> 
> Child should clearly not be allowed to inherit Parent in the code above, 
> since the signature of Child::foo() is more restrictive than the 
> signature of Parent::foo().  The other way around could work (although I 
> don't recall if we allow it):
> 
> class Foo {}
> class Bar extends Foo {}
> 
> class Parent
> {
>         public function foo(Bar $bar){}
> }
> 
> class Child extends Parent
> {
>         public function foo(Foo $foo){}
> }
> 
> 
> No issues here - since any Bar object is also a Foo object and would 
> pass the is_a validation of Foo.  Again, I don't recall if we allow such 
> signature overrides or not.
> 
> Zeev

Guys, this is going a bit nuts, let's swap all the Foo and Bar's for a 
real example - Zeev I've copied the way you specified above.

class Point2D { // Foo
   public $x;
   public $y;
}

class Point3D extends Point2D { // Bar extends Foo
   public $z;
}

class Point2DManager { // Parent
   public function distanceBetween( Point3D $p1 , Point3D $p2 ) {};
}

class Point3DManager extends Point2DManager { // Child extends Parent
   public function distanceBetween( Point2D $p1 , Point2D $p2 ) {};
}

You're saying that makes sense and is no problem? honestly?

Best,

Nathan

ps: no offence / nothing personal just want to get this cleared up