Templates convariance

[Tom S]

michal.minich at gmail.com wrote:
> Thank you for casting solution. It should works perfect for my problem. But
> could you explain me how this can mess things up?

Basically, the fact that Foo is castable to Bar doesn't mean that 
Baz!(Foo) should be castable to Baz!(Bar). Their implementation may be 
totally different based on some static if's and other fancy stuff. IMO 
they are two totally separate classes. If that kind of invariance would 
be to be allowed, then one would sometimes need to specify explicitly 
that a given Baz!(Bar) should not be casted to a Baz!(Foo). And in that 
case, why not reverse the idea and just use the method I provided in the 
remaining cases ? :)


-- 
Tomasz Stachowiak  /+ a.k.a. h3r3tic +/