[Issue 6857] Precondition contract checks should be statically bound.

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=6857



--- Comment #24 from Walter Bright <bugzilla at digitalmars.com> 2012-05-03 18:50:03 PDT ---
(In reply to comment #23)
> (In reply to comment #22)
> >> If you mean whether a given call is legal, then you could by the 
> >> same argument insist that called method names must be resolved in 
> >> the context of the virtual type.
> > 
> > And they are.  It's what the vtbl[] is for.
> 
> ???
> 
> class A {}
> 
> class B : A {
>     void foo() {}
> }
> 
> void main() {
>     A a = new B;
>     a.foo();
> }
> 
> You're claiming that this code is legal, and the penultimate line resolves to
> B's foo method???

No, I'm not. This thread is about overriding, not introducing, functions. 


> I'm surprised that the classic OOP spec covers the behaviour of contracts at
> all.  But maybe I just need to read up on it.

Betrand Meyer's Object Oriented Programming. You can get it on amazon for
$5.99. It's the definitive classic on the topic.

The behavior with contracts is just another aspect of the contravariance and
covariance of derived objects.

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