2017-05-28 12:30 GMT+02:00 Rasmus Schultz <ras...@mindplay.dk>: > > > So this breaks the expected behavior of interfaces. > > > > No it doesn't. It allows interfaces to use contravariance within PHP's > > type system, which is different from before, but it doesn't break > > anything. > > The RFC explicitly states that this is *not* contravariance. >
Where does it state that? (The "true" in the future scope section should probably be replaced with "full".) > And if it's not clear, what I mean by "breaks the expected behavior", is, > as far as I understand, what this RFC actually does is it *removes* > expected behavior. > How does this *remove* expected behavior? Could you show a concrete example of code that breaks? > Correct me if I'm wrong, but really all this RFC does, is remove the > requirement that and implementation of an interface be type-hinted? > Correct, but not just for interfaces. > To me, that's "broken". > As said, please show a concrete example that breaks. > You're favorizing a very, very small number of isolated, valid use-cases - > by removing the normal, natural, expected constraint that an implementation > be type-hinted as specified by the interface. It's part of the reason > interfaces even exist - and this simply ignores that and removes these > checks. > No, interfaces exist to guarantee the caller can always pass a type XY there. With type constraints removed in a subclass, this guarantee does not break. > In my opinion, this will very likely lead to a large number of accidental > type-hint omissions - and a very, very small number of actually useful > solutions to real problems. > > In my opinion, we can do much better than that, by adding a mixed > type-hint, which will ensure people aren't just accidentally omitting > type-hints and instead explicitly opting out of it to achieve parameter > widening. Solving this from the start also ensures we can have a clean > implementation of real contravariance in the future, without that being a > break change. You're, again, ignoring one of the major benefits of the RFC: Being able to move from explicit type checks to type declarations without breaking subclasses. > > Rasmus, not answering people's questions and instead saying emotional > > stuff suggesting other people have made historically bad decisions > > isn't a productive way to conduct a conversation. > > Okay, I'm emotional, sorry about that. > > But I think I'm pointing out a real problem and a real possible solution > that doesn't make the trade-offs of the current solution. > You haven't pointed out a real problem, yet. Regards, Niklas
