interfaces and contracts - new pattern

[Ola Fosheim Grøstad]

On Tuesday, 3 December 2019 at 14:40:21 UTC, Adam D. Ruppe wrote:
> ooooh geeze I was so focused on inheriting the contract that I 
> didn't even test if it didn't have one at all. So we need a

Maybe also test with D interfaces? I suppose they have the same 
behaviour as superclasses?

Anyway, I think most programmers struggle with 
covariant/contravariant parameters... I certainly have to stop up 
and ponder for a while to figure out the semantics when hitting 
such. So I tend to avoid it... :-P :-)