Use WeakRef instead of ObjectSpace::WeakMap?

[nirvdrum]

Mustermann::EqualityMap uses ObjectSpace::WeakMap directly in its implementation. According to the docs for ObjectSpace::WeakMap, that class should not be used directly:

This class is mostly used internally by WeakRef, please use lib/weakref.rb for the public interface.

Of course, it exists and works, but using WeakRef instead looks like the safer option.

[namusyaka]

It looks intentional. weaklef is a really thin wrapper for Object::Weakmap.

I'll let @rkh answer to this issue.

[nirvdrum]

I think that means you're relying on implementation details. TruffleRuby's WeakRef has a different implementation that adheres to the interface, for instance. We don't currently have ObjectSpace::WeakMap, so we fall back to the Array implementation in Mustermann. We'll add ObjectSpace::WeakMap, but this caught my eye as an issue that could also be addressed by using the suggested public interface.