Dependency-injector uses it for exactly this purpose

    @inject
    def main(service: Service = Provide[Container.service]) -> None:
        ...

FastAPI also does a similar sort of trick, for DI and also request parsing.

https://python-dependency-injector.ets-labs.org/introduction...

django-ninja and fastapi does dep injection, parsing and validation based on annotations.

taichi does ffi with their own dsl, cython with c.

I you haven't tried pydantic or sister projects (django-ninja, fastapi and typer), this is a good place to start. They bring a breath of fresh air and are quite fun to use.

It's not one of those that you listed, but the @dataclass decorator uses type hints to auto-generate classes and class constructors (__init__ method) for you.

An example:

    @dataclass
    class HackerNewsPost:
        title: str
        author: str
        votes: int = 0

This will generate a constructor that looks like this:

    def __init__(title: str, author: str, votes: int = 0):
        self.title = title
        self.author = author
        self.votes = votes

This is pretty useful, writing __init__ boilerplate has been a common thing in my experience using Python, and it makes code more compact and readable.

It can do some other things too!

https://docs.python.org/3/library/dataclasses.html

For FFI, there is a pure python mode in cython:

  https://cython.readthedocs.io/en/latest/src/tutorial/external.html