pathlib.Path('.').parent is itself rather than parent

[AdrienHorgnies]

BPO	37486
Nosy	@brettcannon, @pitrou, @AdrienHorgnies

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2019-07-02.15:01:57.579>
created_at = <Date 2019-07-02.14:35:47.998>
labels = ['type-bug', '3.8', '3.9', 'invalid', '3.7', 'library']
title = "pathlib.Path('.').parent is itself rather than parent"
updated_at = <Date 2019-07-02.23:10:31.916>
user = 'https://github.com/AdrienHorgnies'

bugs.python.org fields:

activity = <Date 2019-07-02.23:10:31.916>
actor = 'brett.cannon'
assignee = 'none'
closed = True
closed_date = <Date 2019-07-02.15:01:57.579>
closer = 'pitrou'
components = ['Library (Lib)']
creation = <Date 2019-07-02.14:35:47.998>
creator = 'adrien.pierre.horgnies@gmail.com'
dependencies = []
files = []
hgrepos = []
issue_num = 37486
keywords = []
message_count = 4.0
messages = ['347143', '347145', '347147', '347170']
nosy_count = 3.0
nosy_names = ['brett.cannon', 'pitrou', 'adrien.pierre.horgnies@gmail.com']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue37486'
versions = ['Python 3.7', 'Python 3.8', 'Python 3.9']

[AdrienHorgnies]

Tested with CPython 3.7.3

from pathlib import Path

p = Path('.')

assert p == p.parent # should fail but it does not

I expect Path('.').parent to be Path('..')

I searched issues and did not find any similar issue but maybe I didn't search well enough because I would be surprised that I'd be the first one to be bugged by this issue.

I didn't test newer version of Python as I couldn't find a package or wasn't comfortable enough to build it myself.

[pitrou]

This is by design. The "parent" attribute is a *lexical operation*. If you want to walk the actual filesystem, first call resolve().

It's even documented:
https://docs.python.org/3/library/pathlib.html#pathlib.PurePath.parent

[AdrienHorgnies]

T-T Sorry. It didn't feel intuitive but I should have read the doc...

[brettcannon]

Would it be worth to set 'parent' to None in this instance? Might break code but would also be potentially less surprising.