Return destination path in Path.rename and Path.replace

[albertogomcas]

BPO	31163
Nosy	@jaraco, @pitrou, @bitdancer, @berkerpeksag, @csabella
PRs	bpo-31163: Adding return values to pathlib's rename and replace methods #4055 bpo-31163: Added return values to pathlib.Path instance's rename and replace methods. #13582 [3.8] bpo-31163: Added return values to pathlib.Path instance's rename and replace methods. (GH-13582) #15944

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

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GitHub fields:

assignee = None
closed_at = <Date 2019-09-11.14:23:08.013>
created_at = <Date 2017-08-09.15:32:24.454>
labels = ['easy', '3.8', '3.9', 'type-feature', 'library', 'docs']
title = 'Return destination path in Path.rename and Path.replace'
updated_at = <Date 2019-09-11.14:23:08.008>
user = 'https://bugs.python.org/albertogomcas'

bugs.python.org fields:

activity = <Date 2019-09-11.14:23:08.008>
actor = 'jaraco'
assignee = 'docs@python'
closed = True
closed_date = <Date 2019-09-11.14:23:08.013>
closer = 'jaraco'
components = ['Documentation', 'Library (Lib)']
creation = <Date 2017-08-09.15:32:24.454>
creator = 'albertogomcas'
dependencies = []
files = []
hgrepos = []
issue_num = 31163
keywords = ['patch', 'easy']
message_count = 5.0
messages = ['300019', '300027', '342970', '351865', '351892']
nosy_count = 7.0
nosy_names = ['jaraco', 'pitrou', 'r.david.murray', 'docs@python', 'berker.peksag', 'cheryl.sabella', 'albertogomcas']
pr_nums = ['4055', '13582', '15944']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue31163'
versions = ['Python 3.8', 'Python 3.9']

[albertogomcas]

Extracted from bpo-31154

Both calls lack any kind of return, which leads me to expect after a rename/replace the Path instance would be changed to the new path. This is not the case (reading the PEP I have seen Path instances are kind of immutable), after the call the Path instance keeps "pointing" to the previous (and quite likely now useless) path.

Returning the new path would be a reasonable option. In any case, I think the documentation should mention this behavior explicitly.

[bitdancer]

I agree. The normal python convention is that an immutable object returns the new value when an operation "changes" it, while a mutable object returns None. It seems like replace and rename should follow this convention (and that it would also be convenient).

[csabella]

I've closed the original pull request as the Github user account that created it no longer exists.

[jaraco]

New changeset 088a09a by Jason R. Coombs (hui shang) in branch 'master':
bpo-31163: Added return values to pathlib.Path instance's rename and replace methods. (GH-13582)
088a09a

[jaraco]

New changeset cbd7b2a by Jason R. Coombs (Miss Islington (bot)) in branch '3.8':
bpo-31163: Added return values to pathlib.Path instance's rename and replace methods. (GH-13582) (GH-15944)
cbd7b2a