Output relative path when using PurePath.relative_to

[mhammondr]

BPO	44078
Nosy	@akulakov
Superseder	bpo-40358: pathlib's relative_to should behave like os.path.relpath

^{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 2021-05-14.22:17:49.000>
created_at = <Date 2021-05-08.15:43:11.323>
labels = ['type-feature', 'library', '3.9']
title = 'Output relative path when using PurePath.relative_to'
updated_at = <Date 2022-02-22.23:52:20.218>
user = 'https://bugs.python.org/mhammondr'

bugs.python.org fields:

activity = <Date 2022-02-22.23:52:20.218>
actor = 'Socob'
assignee = 'none'
closed = True
closed_date = <Date 2021-05-14.22:17:49.000>
closer = 'terry.reedy'
components = ['Library (Lib)']
creation = <Date 2021-05-08.15:43:11.323>
creator = 'mhammondr'
dependencies = []
files = []
hgrepos = []
issue_num = 44078
keywords = []
message_count = 2.0
messages = ['393262', '393286']
nosy_count = 3.0
nosy_names = ['Socob', 'andrei.avk', 'mhammondr']
pr_nums = []
priority = 'normal'
resolution = 'duplicate'
stage = 'resolved'
status = 'closed'
superseder = '40358'
type = 'enhancement'
url = 'https://bugs.python.org/issue44078'
versions = ['Python 3.9']

[mhammondr]

Comparing two paths, PurePath.relative_to fails with ValueError if the second path is not in the first.

>>> Path('/a/b').relative_to('/a/b/c')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.9/pathlib.py", line 928, in relative_to
    raise ValueError("{!r} is not in the subpath of {!r}"
ValueError: '/a/b' is not in the subpath of '/a/b/c' OR one path is relative and the other is absolute.

Please extend PurePath.relative_to so it is able to output a relative path in form of '..' instead of an error. Currently, the only way to do this is to use relpath from os.path but it would be very useful if Path was able to output the relative path.

[akulakov]

duplicate of https://bugs.python.org/issue40358 , which has an open patch.

[h-vetinari]

duplicate of https://bugs.python.org/issue40358, which has an open patch.

This should be reopened; the old BPO stuff cannot reasonably be taken as the reference anymore IMO. All the issues moved to github, so this should be documented (and easily searchable) here