make os.scandir work as a context manager #1787

JelleZijlstra · 2017-12-15T05:14:17Z

Rework of #1583. Fixes #1573.

See documentation in https://docs.python.org/3/library/os.html#os.scandir.

To test this, I used the following file:

import os
with os.scandir() as it:
    reveal_type(it)  # _ScandirIterator[str]
    for f in it:
        reveal_type(f)  # DirEntry[str]
with os.scandir(b'.') as bit:
    reveal_type(bit)  # _ScandirIterator[bytes]
    for bf in bit:
        reveal_type(bf)  # DirEntry[bytes]
class BytesPath(os.PathLike[bytes]):
    def __fspath__(self) -> bytes:
        return b'ytes'
with os.scandir(BytesPath()) as bpit:
    reveal_type(bpit)  # _ScandirIterator[bytes]
    for bpf in bpit:
        reveal_type(bpf)  # DirEntry[bytes]

I got

$ mypy --custom-typeshed-dir . samples/scandir.py
samples/scandir.py:3: error: Revealed type is 'os._ScandirIterator*[builtins.str*]'
samples/scandir.py:5: error: Revealed type is 'os.DirEntry*[builtins.str*]'
samples/scandir.py:7: error: Revealed type is 'os._ScandirIterator*[builtins.bytes*]'
samples/scandir.py:9: error: Revealed type is 'os.DirEntry*[builtins.bytes*]'
samples/scandir.py:13: error: Argument 1 to "scandir" has incompatible type "BytesPath"; expected "Union[str, _PathLike[str]]"
samples/scandir.py:14: error: Revealed type is 'os._ScandirIterator*[builtins.str*]'
samples/scandir.py:16: error: Revealed type is 'os.DirEntry*[builtins.str*]'

The error on line 13 is unexpected, but it also appears without this PR. I'll file a bug to mypy for it. (Edit: it's python/mypy#3644.)

Rework of python#1583. Fixes python#1573. See documentation in https://docs.python.org/3/library/os.html#os.scandir.

make os.scandir work as a context manager

e2ad73d

Rework of python#1583. Fixes python#1573. See documentation in https://docs.python.org/3/library/os.html#os.scandir.

JelleZijlstra mentioned this pull request Dec 15, 2017

Change scandir() to type as both iterator and context-manager #1583

Closed

gvanrossum approved these changes Dec 15, 2017

View reviewed changes

matthiaskramm merged commit 4ee508a into python:master Jan 2, 2018

JelleZijlstra deleted the scandirwith branch May 30, 2020 05:07

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make os.scandir work as a context manager #1787

make os.scandir work as a context manager #1787

JelleZijlstra commented Dec 15, 2017 •

edited

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make os.scandir work as a context manager #1787

make os.scandir work as a context manager #1787

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JelleZijlstra commented Dec 15, 2017 • edited Loading

JelleZijlstra commented Dec 15, 2017 •

edited

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