Behaviour of os.path.join

[Roel Schroeven]

BlindAnagram schreef op 27/05/2020 om 18:39:
> On 27/05/2020 16:49, Rhodri James wrote:
>> On 27/05/2020 16:12, BlindAnagram wrote:
>>> I'm sorry that you don't believe me but all I know is how I intend the
>>> path to be used.  And the os.path functions aren't helpful here when
>>> they actually_change_  the meanings of paths on Windows:
>>>
>>>>> fp= "C:\\Documents\finance\\"
>>>>> abspath(fp)
>>> 'C:\\Documents\\finance'
>>>
>>> If you believe these 'before' and 'after' paths are the same I can only
>>> assume that you don't work on Windows (where one refers to a directory
>>> and the other a file without an extension).
>>
>> More accurately, one is not a legal filename but both are legal
>> directory names.
> 
> If they are to be created, which is my situation, the result will be a
> diretory and a file.

os.mkdir('C:\\Documents\\finance') creates a directory.
open('C:\\Documents\\finance', 'w') creates a file.

The difference is in the operation, not in the name.

'C:\\Documents\\finance' is a pathname, which can refer to either a 
directory or a file.
'C:\\Documents\\finance\\' could refer to a directory, but to me looks 
more like a partial pathname, not a complete one.

I can't think of any reason for ending pathnames with (back)slashes. 
Just use os.path.join(directory, filename) when you need to refer to a 
file in the directory.

> I would be surprised if issues such as these were not, at least in
> significant part, the reason why we now have pathlib.

That should be easy to verify: the reasons are listed in the PEP: 
https://www.python.org/dev/peps/pep-0428
I don't see your issue there. I don't think anyone has ever considered 
it an issue at all really.

>> How are these unexpected extensionless files getting created?
> 
> I believe by attempting to make the directory I send absolute with
> abspath() and then copying a file to this path.  They expected this to
> copy the file into the directory with its original name but instead it
> copies it to the file that abspath 'kindly' converts my directory into.

We're getting closer to the real issue here. What functions were used 
copy these files? With which parameters?
Were the destination directories created before copying the files to them?

> I did complain about their lack of knowledge but I also have a right to
> complain about a function that converts an explicitly specified
> directory into a file :-)

Again, a pathname is never inherently a directory or a file.


-- 
"Honest criticism is hard to take, particularly from a relative, a
friend, an acquaintance, or a stranger."
         -- Franklin P. Jones

Roel Schroeven