override(T)

[bearophile]

Andrei Alexandrescu:

> Walter and I discussed last night about contravariance and all and could 
> not find a compelling argument in favor of implementing contravariant 
> arguments right now. The feature is nontrivial to implement, potentially 
> surprising, and has a number of odd corner cases.

Something that may be useful, partially related:
http://en.wikipedia.org/wiki/Multiple_dispatch
http://en.wikipedia.org/wiki/Generic_function

Bye,
bearophile