os.path.join should call os.path.normpath on result

[voidspace]

BPO	6764
Nosy	@loewis, @voidspace

^{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 2009-08-22.22:48:40.047>
created_at = <Date 2009-08-22.21:58:19.631>
labels = ['easy', 'type-bug', 'library']
title = 'os.path.join should call\tos.path.normpath on result'
updated_at = <Date 2009-08-22.22:48:40.046>
user = 'https://github.com/voidspace'

bugs.python.org fields:

activity = <Date 2009-08-22.22:48:40.046>
actor = 'michael.foord'
assignee = 'none'
closed = True
closed_date = <Date 2009-08-22.22:48:40.047>
closer = 'michael.foord'
components = ['Library (Lib)']
creation = <Date 2009-08-22.21:58:19.631>
creator = 'michael.foord'
dependencies = []
files = []
hgrepos = []
issue_num = 6764
keywords = ['easy']
message_count = 3.0
messages = ['91877', '91879', '91881']
nosy_count = 2.0
nosy_names = ['loewis', 'michael.foord']
pr_nums = []
priority = 'normal'
resolution = 'wont fix'
stage = None
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue6764'
versions = ['Python 2.7', 'Python 3.2']

[voidspace]

os.path.join has very basic behavior in the handling of '..'

>>> import os
>>> os.path.join('/foo', '..')
'/foo/..'

For some usecases (comparing paths for example) this is not useful and
you have to manually call normpath on the results:

>>> os.path.normpath(os.path.join('/foo', '..'))
'/'

Because of this code gets littered with annoyingly long chained calls
which are a pain to both read and write.

Is there any problem with join always calling normpath on it's result?

[loewis]

Is there any problem with join always calling normpath on it's result?

Yes. If /usr/local/bin was a symlink to /net/x86, then
/usr/local/bin/../lib might not be /usr/local/lib, but /net/lib. So
calling normpath in the presence of symlinks might be incorrect.

[voidspace]

Damn. :-)

Detecting the case where the normpath'd location is the same means
hitting the filesystem - and the current version just does string
manipulation so it doesn't seem like an acceptable change.

Still, compared to other languages the file handling in Python (spread
across os, os.path, shutil, stat) is clunky and verbose. Fixing that
means duplicating this functionality which makes it unlikely that we'll
get it in the standard library.