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
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