Why Not Os.path.join Use Os.path.sep Or Os.sep?

As we know, windows accept both '\' and '/' as separator. But in python, '\' is used. For example, call os.path.join('foo','bar'), 'foo\\bar' will be returned. What's annoying is t

Solution 1:

To answer your question as simply as possible, just use posixpath instead of os.path.

So instead of:

from os.path import join
join('foo', 'bar')
# will give you either 'foo/bar' or 'foo\\bar' depending on your OS

Use:

from posixpath import join
join('foo', 'bar')
# will always give you 'foo/bar'

Solution 2:

It is all about how Python detects your os:

# in os.py
if 'posix' in _names:
    ...
    import posixpath as path   

elif 'nt' in _names:
    ...
    import ntpath as path

So, on Windows the ntpath module is loaded. If you check the ntpath.py and posixpath.py modules you'd notice that ntpath.join() is a bit more complex and that is also because of the reason you've mentioned: Windows understands / as a path separator.

Bottomline: although you can use posixpath.join() in Windows (as long as the arguments are in POSIX format), I would not recommend doing it.

Solution 3:

Why not define a custom display function?

e.g.

def display_path(path):
    return path.replace("\\", "/")

And if you want to substitute str.join for os.path.join, you can just do this (str.join expects a single list, os.path.join expects *args):

join = lambda *args: "/".join(args)

Perhaps better would be to let Python normalize everything, then replace, e.g.:

join = lambda *args: os.path.join(*args).replace("\\", "/")

The only issue with the above might be on posix when there is a space in the file path.

You could then put an if statement at the top of your utils file and define display_path and join as a no-op and as os.path.join respectively if not on Windows.

Solution 4:

I would not recommend doing this.

Note that while windows does accept slash / as path seperator also, it has a different meaning in some contexts.

It's treated as relative path using cd, for example:

Command line:

c:\Users\YourUser> cd /FooBar
c:\FooBar

Here, / substitutes the drive letter.

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Also, I don't see a problem at all with copying the strings, since if you print the string, the string is displayed as you wish:

Python interpreter:

>>> import os
>>> print os.path.join("c:\", "foo","bar")
c:\foo\bar
>>>

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Solution 5:

I don't have enough reputation to comment, but the above answer is incorrect.

Windows has a concept of working directory and working drive. / is treated as absolute path on your current working drive, since Windows has no concept of single root. In the above example cd /FooBar goes to C:\foobar because the working drive is C:, not because C: is "root" drive or somehow special.

Here's an example:

C:\Users\user> cd /
C:\> d:
D:\> cd /Users
The system cannot find the path specified.
D:\> mkdir test
D:\> cd test
D:\test> cd c:/Users
D:\test> cd /
D:\> cd test
D:\test> c:
C:\Users\> d:
D:\test>