UPath is not a PathLike

[Mr-Pepe]

I upgraded to UPath 0.3.2 and now I am getting type checking errors with basedpyright because __fspath__ is missing.

import os

from upath import UPath

path = UPath(__file__)

os.remove(path)

Basedpyright outputs:

error: Argument of type "UPath" cannot be assigned to parameter "path" of type "StrOrBytesPath" in function "remove"
    Type "UPath" is not assignable to type "StrOrBytesPath"
      "UPath" is not assignable to "str"
      "UPath" is not assignable to "bytes"
      "UPath" is incompatible with protocol "PathLike[str]"
        "__fspath__" is not present
      "UPath" is incompatible with protocol "PathLike[bytes]"
        "__fspath__" is not present (reportArgumentType)
1 error, 0 warnings, 0 notes

Are there any migration instructions I have missed?

[ap--]

Hi @Mr-Pepe

This is indeed a breaking change between 0.2.x and 0.3.x, which was necessary to fix a longstanding bug in UPath. I'll write migration docs and add them to the readme.

Basically os.PathLike objects in Python as well as pathlib.PathPure subclasses represent local filesystem paths. This is only true for the local path UPath subclasses in upath.implementations.local.* and not for example for S3Path.

You can explicitly request UPath to return a FilePath via:

import os

from upath import UPath

path = UPath(__file__, protocol="file")

os.remove(path)

Which your typechecker should correctly accept (unless #435 interferes with it right now).

Your code example would for example be incorrect at runtime if it would run with a memory path:

import os

from upath import UPath

path = UPath("memory:///file.txt")

os.remove(path)

For testing against the different path types UPath 0.3.x introduces upath.types and specifically the following *PathLike classes:

universal_pathlib/upath/types/__init__.py

Lines 45 to 48 in 70826a2

	SupportsPathLike: TypeAlias = Union[VFSPathLike, PathLike[str]]
	JoinablePathLike: TypeAlias = Union[JoinablePath, SupportsPathLike, str]
	ReadablePathLike: TypeAlias = Union[ReadablePath, SupportsPathLike, str]
	WritablePathLike: TypeAlias = Union[WritablePath, SupportsPathLike, str]

[Mr-Pepe]

@ap-- Thank you so much for the fast response!

I just tried different type checkers. They all raise an error without the protocol argument. With protocol="file", I get the following results:

✅ Mypy
✅ Pyrefly
❌ Pyright
❌ Basedpyright

Pyright still infers UPath as the type. Should I raise an issue on the pyright issue tracker?

Other than that, adding migration docs is a great idea 👍

[ap--]

Not sure if reporting to pyright and basedpyright makes sense right now.

I first need to write a few minimal examples, as in here: #435 (comment) because it seems neither of the typecheckers fully support overloading __new__ or type.__call__ yet...