Implement file handling independent of aiofiles, add support for file-like objects

[tiangolo]

This PR removes aiofiles as a dependency, handling files directly.

It also adds support for file-like objects in FileResponse apart from file paths.

This is related to #461 and @tomchristie's comment at #457 (comment)

[florimondmanca]

Good stuff!

Any reason why changing path to file_or_path instead of adding a new file parameter, and making sure only one of them is given? Would preserve the current API on FileResponse.

[tiangolo]

Good point. Many libraries receive a file or path single parameter, this would be equivalent to that. E.g. Pillow: https://pillow.readthedocs.io/en/3.1.x/reference/Image.html#PIL.Image.open

But having just an additional parameter would work the same.

@tomchristie what do you prefer?

[dhirschfeld]

An argument which can take either a file-like object or a path is quite a common idiom in Python and is, IMHO quite a user-friendly api.

• https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.read_csv.html#pandas-read-csv
• https://docs.scipy.org/doc/numpy/reference/generated/numpy.loadtxt.html#numpy-loadtxt
• https://matplotlib.org/3.1.1/api/_as_gen/matplotlib.pyplot.savefig.html#matplotlib-pyplot-savefig

Exposing two different arguments to a user and forcing them to choose depending on the type of object they have doesn't strike me as very pythonic - Python is duck-typed so the user shouldn't have to care about the type of argument they pass - the class should handle those details internally (as is done in this PR)

[Kludex]

Hola @tiangolo 👋

Closing this due to recent anyio integration and aiofiles removal on #1157.

[tiangolo]

Nice! Thanks @Kludex for the cleanup. 🙇