How to do relpath implementation on 2.5
rylesny at gmail.com
Sun Aug 9 09:49:42 CEST 2009
On Aug 8, 9:08 pm, Brian Allen Vanderburg II
<BrianVanderbu... at aim.com> wrote:
> I've coded my own 'relpath' implementation for 2.5 (shown below) and I
> want to make sure it follows as closely as it should to 2.6 and later.
> I've got a question regarding that. When attempting to convert to a
> relative path and it is not possible for some reason (different drive or
> UNC share), should that be an error or should it return the absolute
> path of the target? I'm using Debian so I don't have 2.6 available
> right now for testing.
Usually Python source code is easily browsed at:
Unfortunately the server is down right now.
The implementation in 2.6 raises a ValueError exception. Here is the
function from ntpath.py:
def relpath(path, start=curdir):
"""Return a relative version of a path"""
if not path:
raise ValueError("no path specified")
start_list = abspath(start).split(sep)
path_list = abspath(path).split(sep)
if start_list.lower() != path_list.lower():
unc_path, rest = splitunc(path)
unc_start, rest = splitunc(start)
if bool(unc_path) ^ bool(unc_start):
raise ValueError("Cannot mix UNC and non-UNC paths (%s and
raise ValueError("path is on drive %s, start on drive %s"
# Work out how much of the filepath is shared by start and path.
for i in range(min(len(start_list), len(path_list))):
if start_list[i].lower() != path_list[i].lower():
i += 1
rel_list = [pardir] * (len(start_list)-i) + path_list[i:]
if not rel_list:
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