get_or_default

[arcnmx]

Also exposes Implements publicly so that it can be used as a generic bound in external crates.

[reem]

I'd like to hear what the use case for Implements in another crate is, I originally meant to keep it internal. I'm not sure it's really worth having a method for something that's already a simple one-liner out of composable pieces, do you have some specific case that this makes prettier? I would be more open to an or_default method on the Entry object directly, since that seems more fine-grained.

[arcnmx]

The thing about a private Implements is that it makes it impossible to write extension traits or generic methods that call the AnyMap methods over a generic TypeMap<A>, since you can't express the type bounds on a generic Key::Value. So, for example, a method much like get_or_default is super heavily used in my codebase, and it simply can't be abstracted away: I have to expose a mutable reference to the TypeMap field directly and then maybe use a macro if I wanted to shorten it.

[reem]

So if Implements was public, you would be fine without get_or_default?

[arcnmx]

Sure, that seems fine to me. From my reading of RFC 136, it sounds like a bug that the compiler allows it to be private at all..?