[Python-Dev] file system path protocol PEP (original) (raw)

Brett Cannon brett at python.org
Thu May 12 15🔞12 EDT 2016

On Thu, 12 May 2016 at 12:03 Guido van Rossum <guido at python.org> wrote:

On Thu, May 12, 2016 at 11:51 AM, Brett Cannon <brett at python.org> wrote:

Anyway, with your strong preference of how to tweak os.fspath() what specifically would you like to see discussed at this point? Preferably nothing. :-) There's been too much discussion already.

Works for me. :) I'll update the PEP with the new semantics for os.fspath() and send out the updated version later today.

Assuming the os.fspath() -> bytes discussion is dealt with, the only open issues listed in the PEP are the naming and placement of the ABC and how to do type hints for all of this (thanks to the dichotomy of path objects using the protocol and path-like objects which is the union of path object, str, and bytes and the joy of trying to name all of this well). Name and placement: I think it belongs in os, and os.PathLike sounds like a fine name. (I'm surprised that os.DirEntry doesn't exist.)

SGTM. And os.DirEntry doesn't exist simply because it's posix.DirEntry since it's implemented entirely in C. We could add an alias but since it isn't constructed from scratch I don't think it's worth it.

Typing: do you want it to be a generic class? If not, the types can be left out of the stdlib and only put in the stub (though you can show them in the PEP of course).

If we aren't going to restrict what os.fspath() returns then I don't see any need to make the type generic (I mean technically a generic version might be nice for e.g. the constructor of pathlib only taking strings, but it's probably overkill).

I guess my real question is whether we want to create typing.PathLike to match os.PathLike? And it sounds like you don't want to bother with a potential second type that corresponds to Union[str, bytes, PathLike].

If you want it to be generic we have more work to do. I'm out of time now but we can discuss that after 3pm today.

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