----- "Nathan Rixham" <[email protected]> wrote:
> Chris Stockton wrote:
> > Hello,
> >
> > On Thu, Aug 19, 2010 at 12:33 PM, Nathan Rixham <[email protected]>
> wrote:
> >> 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.
> >
> > I think your misunderstanding his position. To summarize my
> > understanding: he clearly states that in such a use case a warning
> is
> > in order, however currently the warning is overly aggressive. I
> think
> > in general this is a small fish in the pond but I see his point.
> >
>
> Perhaps I am, I think his example was wrong - if it was an example of
>
> doing it the wrong way and an example which should trigger a warning
> then yes I totally agree.
>
> To clarify, hopefully - given:
>
> class Point2D {}
> class Point3D extends Point2D {}
>
> the following is incorrect and should raise a (heavy) warning (Zeev's
>
> example with class names changed for clarity):
>
> class Point2DManager {
> public function distanceBetween( Point3D $p1 , Point3D $p2 ) {};
> }
> class Point3DManager extends Point2DManager {
> public function distanceBetween( Point2D $p1 , Point2D $p2 ) {};
> }
>
No, this is correct. Even though stupid in this case, it is supposed to be
correct.
> whilst the following is correct, and should not raise any warning:
>
> class Point2DManager {
> public function distanceBetween( Point2D $p1 , Point2D $p2 ) {};
> }
> class Point3DManager extends Point2DManager {
> public function distanceBetween( Point3D $p1 , Point3D $p2 ) {};
> }
>
This is incorrect. Any class extending Point2DManager should be able to provide
at least as much functionality as the parent class. In other words, it should
not tighten the pre-conditions.
In your case, Point3dmanager will no longer be able to handle 2dpoints, which
is a mistake.
> If we're all saying the same thing then great and apologies for the
> confusion.
>
> Best,
>
> Nathan
>
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