[issue1669539] Fix bug in os.path.join

[Terry J. Reedy]

Terry J. Reedy <tjreedy at udel.edu> added the comment:

A bug for tracker purposes is a discrepancy between doc and code. That can be fixed in current versions. A design change is a feature request and can only go in future versions. A deprecation warning for one cycle is desirable when appropriate.

"os.path.isabs(path) 
Return True if path is an absolute pathname. On Unix, that means it begins with a slash, on Windows that it begins with a (back)slash after chopping off a potential drive letter."

>From what you report, the code does just that, so there is no bug.
Breaking code just because you do not like the current definition is very unlikely to be accepted.

Adding a .isrelative(path) that seems to be equivalent to 'not .ispath' is unlikely to accepted. People who care about the presence of a drive letter can write "path[1]==':'"

"os.path.join(path1[, path2[, ...]]) 
Join one or more path components intelligently. If any component is an absolute path, all previous components (on Windows, including the previous drive letter, if there was one) are thrown away, and joining continues."

>>> import os
>>> os.path.join('foo', 'a:bar')
'foo\\a:bar'

Producing a non-path does not seem intelligent, so I agree that this a bug. I am not sure what this should produce. 'foo/bar', 'a:foo/bar', and raising an exception would be candidates. All would be better than the current useless return. In any case, a bug fix patch can only fix bugs and should not be intermixed with feature patches.

As to the second sentence: your proposal to change documented and inplemented semantics is, again, a feature request, not a bug fix.

If you want to continue with your feature requests, you can if you wish reclassify this issue, retitle again, and open a new behavior issue for the path bug and upload a bugfix-only patch. Before or along with doing so, I would suggest discussion on the python-ideas list.

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nosy: +terry.reedy -BreamoreBoy
title: Change (fix!) os.path.isabs() semantics on Win32 -> Fix bug in os.path.join
versions: +Python 3.3 -Python 2.6, Python 3.1

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<http://bugs.python.org/issue1669539>
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