Give some sentinel enums for Python cases translatable to TS types without counterpart

[guillaume-mueller]

Having to somewhat definitely choose to treat None as null or undefined seems not ideal in the long term.

Plus Python using None for functions not returning anything is not even compatible.

What about some explicit sentinel enums the user can give to py2ts.generate_ts for the TS types without Python counterparts such as unknown, void and undefined, in order to fluently makes them corresponds to the logic of the inspection flow.

This way one could for example do the following without having to treat special cases before calling py2ts.generate_ts:

def function(arg):
    ...

type_hints = get_type_hints(function)

arg_type_hint = type_hints.get('arg', py2ts.enums.unknown)
arg_ts_type = py2ts.generate_ts(arg_type_hint)

return_type_hint = type_hints.get('return', py2ts.enums.void)
return_ts_type = py2ts.generate_ts(return_type_hint)

[semohr]

Heya, thanks for your interest in the project!

I originally started this to convert TypedDicts into TypeScript interfaces. In that context, translating None to null made the most sense to me, especially since we also use NotRequired to represent optional fields, which maps nicely to either the ? operator or undefined, depending on preference. That’s how we currently handle it in [beets-flask](https://github.com/pSpitzner/beets-flask) and some other private projects.

I agree it's not ideal for functions, but supporting function translation wasn’t really a goal for this tool. I don’t have plans to add that for now. That said, if you'd like to improve or extend the functionality, feel free to open a PR! I'm happy to approve most changes 🙃 Adding support for things like sentinel enums should definitely be doable and would only need a small if any code changes.

[guillaume-mueller]

Thanks for the explanation.

I want to use your project to automatically declare functions exposed by the packages python-socketio / flask-socketio to the JS one Socket.IO.

I'm already doing pretty well with a simple dictionary mapping, but the support of your project for recursive inner types is very interesting.

I don't see any obstacle to use it to for whole functions declarations.

I may contribute at some point.

[semohr]

That makes sense, it's probably due to the example I included in the docs.

I think that use case should definitely be possible. If you have a concrete example in mind, feel free to contribute it to the docs, happy to include it!

It’s a bit heavier, but if your use case aligns, you might also find something like tRPC interesting. I think they do have a python and js integrations. I opted against it as it is too heavy for my usecase and I like to create most things in my stack myself as an exercise ;)