how to get isinstance() to pass?

[LegNeato]

I want my Rust code to pass a python isinstance() check for the standard python Uuid class. Is this currently supported?

(I think I might have asked this in chat months ago but can't find the answer)

[birkenfeld]

Tricky: the magic method __instancecheck__ exists to allow this, but it must be defined in the metaclass. I don't think we do anything with metaclasses in PyO3 so far.

This is why isinstance is not idiomatic Python in most cases. It quacks like a duck etc.

[LegNeato]

Yeah, I guess I can patch it in Django but it will take time for it to release and for us to upgrade :-(

[birkenfeld]

Creating types with custom metaclass seems to be hard to impossible (for abi3) right now from the C API. See https://bugs.python.org/issue15870 for a discussion.

[LegNeato]

Looks like there is a task tracking: #906