Unsupported class decorator

[ijustlovemath]

Saw this project on HN and wanted to try it out! In my application there's a class used to keep track of other eligible classes using a decorator. This is great for automatically adding new functionality by just plopping a decorator onto a class, but it's not supported.

Using codon 0.15.2

Here's a minimal example:

a.py

class Keeper:
    stuff = []

    @classmethod
    def register(cls, thing):
        cls.stuff.append(thing)
        return thing

@Keeper.register
class Car:
    pass

@Keeper.register
class Boat:
    pass

for thing in Keeper.stuff:
    print(thing.__name__)

When run, I get the following output:

% codon build a.py
a.py:9:2-17: error: unsupported class decorator

I ran this from WSL Debian, but that hopefully shouldn't matter. Let me know if you need any other information

[inumanag]

Codon does not yet support class decorators and metaclasses (with some very limited exceptions; e.g., dataclass).

No ETA is available at the moment as it's not a trivial fix. If there's a widespread interest in this feature, however, we'll prioritize it.

[ijustlovemath]

Sounds good! I think I'm probably not alone in my love of class decorators, they let you do some nice Pythonic things. Totally understand that they're probably hell to fit into a static typing system, though. Metaclasses are a little beyond where I've ever needed to go, so if there's a happy medium, you'd definitely cover my use case.

Thanks for your work on this project!

[ShalokShalom]

This fails for me for dataclass. This seems to be unintended?

P.S: I think @final, and generally custom decorators (with @wrap, or renamed ones, like data = partial(dataclass, slots=True, frozen=typing.TYPE_CHECKING) is an important area as well.

I like to implement a tagged union, and hope that would be supported by Codon. 😢

[inumanag]

Please see #606 to track the implementation progress.