On Tuesday, 3 December 2019 at 15:12:46 UTC, Ola Fosheim Grøstad
wrote:
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.
Also the use of the term "covariant" here is confusing to me:
https://dlang.org/spec/function.html
My understanding is that covariant means that an enclosing type
and the enclosed type have the same typing-relationship when
specialized. Whereas contravariant means they are opposite. So
you need two types for it to make sense. I.e. the schematic here:
https://en.wikipedia.org/wiki/Covariance_and_contravariance_(computer_science)#Inheritance_in_object-oriented_languages
But it the documentation "covariant" is used to describe a simple
subtyping-relationship on one type?
Anyway, the wording is confusing. I think it would be hard on
newbies, even if it was correctly used.
