how having the basename of a file or directory

how having the basename of a file or directory

[Thierry Volpiatto]

Hi all,
i didn't find any function giving the basename of a file or directory.
I use this actually:


(defun basename (fname)
  (if (file-directory-p fname)
      (let ((dirname (directory-file-name fname))) 
        (file-relative-name
         dirname (file-name-directory dirname)))
      (file-name-nondirectory fname)))

Does it exists already something i missed?

-- 
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how having the basename of a file or directory

[Stephen J. Turnbull]

Thierry Volpiatto writes:

 > (defun basename (fname)
 >   (if (file-directory-p fname)
 >       (let ((dirname (directory-file-name fname))) 
 >         (file-relative-name
 >          dirname (file-name-directory dirname)))
 >       (file-name-nondirectory fname)))

(file-name-nondirectory (directory-file-name PATH))

should work (modulo I'm testing in XEmacs, but I can't imagine that we
differ in this respect).

Re: how having the basename of a file or directory

[Thierry Volpiatto]

Hi Stephen,

"Stephen J. Turnbull" <stephen@xemacs.org> writes:

> Thierry Volpiatto writes:
>
>  > (defun basename (fname)
>  >   (if (file-directory-p fname)
>  >       (let ((dirname (directory-file-name fname))) 
>  >         (file-relative-name
>  >          dirname (file-name-directory dirname)))
>  >       (file-name-nondirectory fname)))
>
> (file-name-nondirectory (directory-file-name PATH))
>
> should work (modulo I'm testing in XEmacs, but I can't imagine that we
> differ in this respect).
Yes thanks, that's work too, but it would be nice to do not have to take
care of that:

(file-name-nondirectory "path/to/a/directory")
should return ==> directory
(file-name-nondirectory "path/to/a/file")
should return ==> file

So modifying `file-name-nondirectory' or creating a basename function
or macro like:

(defun basename (fname)
  (if (file-directory-p fname)
      (let ((dirname (directory-file-name fname)))
        (file-name-nondirectory dirname))
      (file-name-nondirectory fname)))

would be nice.


-- 
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Re: how having the basename of a file or directory

[Andreas Schwab]

Thierry Volpiatto <thierry.volpiatto@gmail.com> writes:

> (file-name-nondirectory "path/to/a/directory")
> should return ==> directory

It does.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
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"And now for something completely different."

Re: how having the basename of a file or directory

[Thierry Volpiatto]

Andreas Schwab <schwab@linux-m68k.org> writes:

> Thierry Volpiatto <thierry.volpiatto@gmail.com> writes:
>
>> (file-name-nondirectory "path/to/a/directory")
>> should return ==> directory
>
> It does.
Not really.
It does if PATH doesn't end with "/" otherwise no, it's why

(file-name-nondirectory (directory-file-name PATH)) 

is needed as Stephen said.

You see, it's confusing ;-)

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Re: how having the basename of a file or directory

[Andreas Schwab]

Thierry Volpiatto <thierry.volpiatto@gmail.com> writes:

> Andreas Schwab <schwab@linux-m68k.org> writes:
>
>> Thierry Volpiatto <thierry.volpiatto@gmail.com> writes:
>>
>>> (file-name-nondirectory "path/to/a/directory")
>>> should return ==> directory
>>
>> It does.
> Not really.
> It does if PATH doesn't end with "/" otherwise no, it's why

file-name-nondirectory doesn't care whether the argument is a directory
or not, it looks only at the contents of the string.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
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"And now for something completely different."

Re: how having the basename of a file or directory

[Thierry Volpiatto]

Andreas Schwab <schwab@linux-m68k.org> writes:

> Thierry Volpiatto <thierry.volpiatto@gmail.com> writes:
>
>> Andreas Schwab <schwab@linux-m68k.org> writes:
>>
>>> Thierry Volpiatto <thierry.volpiatto@gmail.com> writes:
>>>
>>>> (file-name-nondirectory "path/to/a/directory")
>>>> should return ==> directory
>>>
>>> It does.
>> Not really.
>> It does if PATH doesn't end with "/" otherwise no, it's why
>
> file-name-nondirectory doesn't care whether the argument is a directory
> or not, it looks only at the contents of the string.
Yes, i understood that, i am just pointing out that we should not have
to take care if string end with / or not, like shell command basename.

basename /home/thierry/riri
riri
basename /home/thierry/riri/
riri

-- 
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Re: how having the basename of a file or directory

[Andreas Schwab]

Thierry Volpiatto <thierry.volpiatto@gmail.com> writes:

> Andreas Schwab <schwab@linux-m68k.org> writes:
>
>> Thierry Volpiatto <thierry.volpiatto@gmail.com> writes:
>>
>>> Andreas Schwab <schwab@linux-m68k.org> writes:
>>>
>>>> Thierry Volpiatto <thierry.volpiatto@gmail.com> writes:
>>>>
>>>>> (file-name-nondirectory "path/to/a/directory")
>>>>> should return ==> directory
>>>>
>>>> It does.
>>> Not really.
>>> It does if PATH doesn't end with "/" otherwise no, it's why
>>
>> file-name-nondirectory doesn't care whether the argument is a directory
>> or not, it looks only at the contents of the string.
> Yes, i understood that, i am just pointing out that we should not have
> to take care if string end with / or not, like shell command basename.

file-name-nondirectory is not basename.  The empty string is a valid
file name in Emacs.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
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"And now for something completely different."

Re: how having the basename of a file or directory

[Stefan Monnier]

> Yes thanks, that's work too, but it would be nice to do not have to take
> care of that:

> (file-name-nondirectory "path/to/a/directory")
> should return ==> directory

It does.

> (file-name-nondirectory "path/to/a/file")
> should return ==> file

It does.

> So modifying `file-name-nondirectory' or creating a basename function
> or macro like:

> (defun basename (fname)
>   (if (file-directory-p fname)
>       (let ((dirname (directory-file-name fname)))
>         (file-name-nondirectory dirname))
>       (file-name-nondirectory fname)))

That won't work on (basename "/non/existing/thing/").
You really want to use (file-name-nondirectory (directory-file-name fname))


        Stefan

Re: how having the basename of a file or directory

[Thierry Volpiatto]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> Yes thanks, that's work too, but it would be nice to do not have to take
>> care of that:
>
>> (file-name-nondirectory "path/to/a/directory")
>> should return ==> directory
>
> It does.
>
>> (file-name-nondirectory "path/to/a/file")
>> should return ==> file
>
> It does.
>
>> So modifying `file-name-nondirectory' or creating a basename function
>> or macro like:
>
>> (defun basename (fname)
>>   (if (file-directory-p fname)
>>       (let ((dirname (directory-file-name fname)))
>>         (file-name-nondirectory dirname))
>>       (file-name-nondirectory fname)))
>
> That won't work on (basename "/non/existing/thing/").
> You really want to use (file-name-nondirectory (directory-file-name fname))
Indeed, yes, thanks Stefan, but something like


(defun basename (fname)
  (if (or (file-directory-p fname)
          (string-match "/$" fname))
      (let ((dirname (directory-file-name fname))) 
        (file-name-nondirectory dirname))
      (file-name-nondirectory fname)))

would work and be useful.

-- 
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Re: how having the basename of a file or directory

[Karl Fogel]

I think Thierry's point is that it would be useful for Emacs to have a
function called "basename", that does what functions of similar name do
in other programming language standard libraries and in the shell.

FWIW, I agree.  Many times I've done an Apropos search on "basename",
only to remember that there's some complicated recipe involving
`file-name-nondirectory' (which I then go look up).

Now, what the exact behavior of `basename' should be is open to debate.
Perhaps it should be:

  (defun basename (path)
    (file-name-nondirectory (directory-file-name path)))

Or perhaps it should be:

  (defun basename (path)
    (thing-thierry-recently-defined))

Or perhaps something else.

Can we treat the two questions separately, though?  If we agree that
having something called `basename' in Emacs Lisp would be good, then we
can probably quickly agree on exactly how it should behave, so let's
start with the first question: should we have `basename'?

-Karl

Thierry Volpiatto <thierry.volpiatto@gmail.com> writes:
>Stefan Monnier <monnier@iro.umontreal.ca> writes:
>
>>> Yes thanks, that's work too, but it would be nice to do not have to take
>>> care of that:
>>
>>> (file-name-nondirectory "path/to/a/directory")
>>> should return ==> directory
>>
>> It does.
>>
>>> (file-name-nondirectory "path/to/a/file")
>>> should return ==> file
>>
>> It does.
>>
>>> So modifying `file-name-nondirectory' or creating a basename function
>>> or macro like:
>>
>>> (defun basename (fname)
>>>   (if (file-directory-p fname)
>>>       (let ((dirname (directory-file-name fname)))
>>>         (file-name-nondirectory dirname))
>>>       (file-name-nondirectory fname)))
>>
>> That won't work on (basename "/non/existing/thing/").
>> You really want to use (file-name-nondirectory (directory-file-name fname))
>Indeed, yes, thanks Stefan, but something like
>
>
>(defun basename (fname)
>  (if (or (file-directory-p fname)
>          (string-match "/$" fname))
>      (let ((dirname (directory-file-name fname))) 
>        (file-name-nondirectory dirname))
>      (file-name-nondirectory fname)))
>
>would work and be useful.

Re: how having the basename of a file or directory

[Stefan Monnier]

> (defun basename (fname)
>   (if (or (file-directory-p fname)
>           (string-match "/$" fname))
>       (let ((dirname (directory-file-name fname))) 
>         (file-name-nondirectory dirname))
>       (file-name-nondirectory fname)))

If, as Karl suggests, your point is that you want a `basename' function,
then maybe we could add such a function (I'm really not convinced it's
worth the trouble.  Better would be to add a paragraph in the manual,
I think), but I still insist that the above definition is wrong.
It should be

  (defun file-basename (file)
    (file-name-nondirectory (directory-file-name file)))


-- Stefan

Re: how having the basename of a file or directory

[Thierry Volpiatto]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> (defun basename (fname)
>>   (if (or (file-directory-p fname)
>>           (string-match "/$" fname))
>>       (let ((dirname (directory-file-name fname))) 
>>         (file-name-nondirectory dirname))
>>       (file-name-nondirectory fname)))
>
> If, as Karl suggests, your point is that you want a `basename' function,
> then maybe we could add such a function (I'm really not convinced it's
> worth the trouble.  Better would be to add a paragraph in the manual,
> I think), but I still insist that the above definition is wrong.
The above definition is not wrong, but it have unneeded code.
However the unneeded code explain clearly what happen.

> It should be
>
>   (defun file-basename (file)
>     (file-name-nondirectory (directory-file-name file)))
Yes.
Because the name of this function (i.e directory-file-name), i didn't think
to call it on a filename, but it return the filename yes.
Maybe confusion with file-name-directory.
(always need to look manual when using all these file-name-*,
directory-file-* etc... functions)

Adding a basename function is just a first step to simplify all that.

-- 
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Re: how having the basename of a file or directory

[Stephen J. Turnbull]

Thierry Volpiatto writes:

 > (file-name-nondirectory "path/to/a/directory")
 > should return ==> directory
 > (file-name-nondirectory "path/to/a/file")
 > should return ==> file

They do.

(file-name-nondirectory "path/to/a/directory/") => ""

is the problem.

 > So modifying `file-name-nondirectory'

This is probably out of the question.  It should be the case that

(equal fname (concat (file-name-directory fname)
                     (file-name-nondirectory fname))))

 > or creating a basename function

Un-Pythonic.  But then, this isn't Python, so I guess it's OK. ;-)

Re: how having the basename of a file or directory

[Karl Fogel]

"Stephen J. Turnbull" <stephen@xemacs.org> writes:
> > or creating a basename function
>
>Un-Pythonic.  But then, this isn't Python, so I guess it's OK. ;-)

  $ python
  Python 2.6.6 (r266:84292, Dec 27 2010, 00:02:40) 
  >>> import os.path
  >>> os.path.basename("/home/kfogel/README")
  'README'
  >>> quit()
  $ 

Re: how having the basename of a file or directory

[Stephen J. Turnbull]

Karl Fogel writes:
 > "Stephen J. Turnbull" <stephen@xemacs.org> writes:
 > > > or creating a basename function
 > >
 > >Un-Pythonic.  But then, this isn't Python, so I guess it's OK. ;-)
 > 
 >   $ python
 >   Python 2.6.6 (r266:84292, Dec 27 2010, 00:02:40) 
 >   >>> import os.path
 >   >>> os.path.basename("/home/kfogel/README")
 >   'README'
 >   >>> quit()
 >   $ 

You know what I mean.  "Not every three-line function needs to be a
built-in."  AFAIK Python doesn't have an equivalent to
file-name-directory; you need to write that yourself.

Re: how having the basename of a file or directory

[Karl Fogel]

"Stephen J. Turnbull" <stephen@xemacs.org> writes:
>Karl Fogel writes:
> > "Stephen J. Turnbull" <stephen@xemacs.org> writes:
> > > > or creating a basename function
> > >
> > >Un-Pythonic.  But then, this isn't Python, so I guess it's OK. ;-)
> > 
> >   $ python
> >   Python 2.6.6 (r266:84292, Dec 27 2010, 00:02:40) 
> >   >>> import os.path
> >   >>> os.path.basename("/home/kfogel/README")
> >   'README'
> >   >>> quit()
> >   $ 
>
>You know what I mean.  "Not every three-line function needs to be a
>built-in."  AFAIK Python doesn't have an equivalent to
>file-name-directory; you need to write that yourself.

Oh, sorry -- I didn't actually know that's what you meant.

(Sometimes people use "Pythonic" to mean "whatever matches my taste";
you were being more careful than that, but unfortunately it was lost on
me because I've been too degraded by other conversations.)

FWIW, for me the compelling argument for a `basename' function is that
then M-x apropos will find it (and programmers often need it).  Given
that "basename" seems to have become the standard term for this
functionality, we should take the simplest step that makes it findable
via that term.  If there's some other method that will accomplish the
same thing, that's fine.

-Karl

Re: how having the basename of a file or directory

[Stephen J. Turnbull]

Karl Fogel writes:

 > FWIW, for me the compelling argument for a `basename' function is that
 > then M-x apropos will find it (and programmers often need it).

Both points are true, but I find it a little less than compelling.  I
use "filename" with apropos in this context.

The argument you make is similar to the arguments often made for
changing or aliasing "kill" to "cut" and "yank" to "paste", and I find
them not quite compelling, too.  Emacs is different from other
applications; "kill" and "yank" are quite a bit more general (and
useful) in Emacs than "cut" (to clipboard) and "paste" (to clipboard)
IMO.  (I guess with modern clipboards that can handle multiple
cuttings you can do the same kinds of things that you can do with
Emacs's kill-ring, but I don't know anybody who actually does, a
strong contrast to Emacs practice.)

YMMV, IMHO of course.