Re: Sorting directory-files on their extension

[pjb@informatimago.com (Pascal J. Bourguignon)]

Nordlöw <per.nordlow@gmail.com> writes:

> On Oct 7, 4:35 pm, Nordlöw <per.nord...@gmail.com> wrote:
>> Does Emacs contain any built-in features for sorting file-names (list
>> of strings) on their (file) extension?
>>
>> /NOrdlöw
>
> Is this a good candidate?:
>
> (defun compare-extensions (a b)
>   (compare-strings
>    (file-name-extension a) 0 (length (file-name-extension a))
>    (file-name-extension b) 0 (length (file-name-extension b))))
> ;; Use: (sort '("a.c" "a.h" "b.c" "b.h") 'compare-extensions)

No, it doesn't work because compare-strings always return true, while
sort expects an order function that returns true only when a<b.

  (string< (file-name-extension a) (file-name-extension b))

is what you'd want.  If you want it case insignificant, you can use

  (string< (upcase (file-name-extension a))
           (upcase (file-name-extension b)))


-- 
__Pascal Bourguignon__