interfaces and contracts - new pattern

[Ola Fosheim Grøstad]

On Tuesday, 3 December 2019 at 14:51:58 UTC, Adam D. Ruppe wrote:
> Maybe, but it is pretty sound once you get to know it.

You mean contracts? Yes. But I was thinking of 
contravariant/covariant parameters on virtual functions. Doesn't 
work with overloading though, so D only has it on return types? 
Probably for the best. Perhaps.