[Patches] [ python-Patches-1339796 ] new function: os.path.relpath

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Patches item #1339796, was opened at 2005-10-27 11:23
Message generated for change (Comment added) made by nnorwitz
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Category: Library (Lib)
Group: Python 2.5
Status: Open
Resolution: None
Priority: 5
Submitted By: Richard Barran (rbarran)
Assigned to: Nobody/Anonymous (nobody)
Summary: new function: os.path.relpath

Initial Comment:
Hello,

This patch adds a 'relpath' function to module os.path
as per RFE #1309676 and also this thread:
http://mail.python.org/pipermail/python-dev/2005-September/056709.html

Here's a description of this function:
"relpath(path, start=os.curdir) 
Return a relative filepath to 'path' either from the
current directory or from a specified 'start' point."

This patch includes Windows and *nix versions. 
It has been tested on Windows XP and OS/X 10.4.

Note: there is no 'classic mac' version as I don't know
that platform :-(

Changed files are: 
lib/ntpath.py 
lib/test/test_ntpath.py 
lib/posixpath.py 
lib/test/test_posixpath.py

I'll send a second patch for the documentation shortly.

As this is my first submission please be gentle with me
if there are any basic errors :-)

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>Comment By: Neal Norwitz (nnorwitz)
Date: 2005-10-27 23:21

Message:
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Thanks for the patch, it's not in bad shape.  Please attach
the doc patch file here.  It's easier to have a single patch
than multiple.

A couple of things about the patch.  Some of these should be
in PEP 8.
 * <> is deprecated in favor of != (didn't see this doc'd in
PEP 8 though, maybe it's in another PEP)
 * don't add extra parentheses, e.g.,
(abspath(start)).split(sep) should be abspath(start).split(sep)
 * I'm not sure it's worth checking that there's a path.  I
noticed that abspath() didn't have a similar check.  I
didn't look for other places, but doubt there is much error
checking since a reasonable exception should be raised.
 * The for loop is a lot to swallow.  It would be easier to
read if you used a local variable for the min_len IMO.
 * I'd like to see a test case for: relpath("a", "a")
 * I'd like to see test cases in ntpath for paths with a
drive letter
 * I'd like to see test cases for the exceptions raised in
ntpath

Another note that isn't a big deal.  It's good that you made
a single patch file.  I think most other developers prefer
the patch to start one level up.  ie, don't start in Lib/,
include it in the patch.  I certainly prefer it this way so
I don't have to cd much.  It just makes development a little
easier.

You can attach new versions to this tracker item, but try to
remember to add a description that says version # so no one
reviews an older version.

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