Lars Ingebrigtsen <larsi@gnus.org> writes:

> Alex Bochannek <alex@bochannek.com> writes:
>
>> Since I was able to get the Newsgroups extra header working for
>> `nnvirtual' groups, I would like to not only limit, but also sort by the
>> extra headers.
>
> Looks good; applied with one minor tweak:
>
>> +(defun gnus-article-sort-by-newsgroups (h1 h2)
>> +  "Sort articles by newsgroups."
>> +  (gnus-string<
>> +   (let ((extract (funcall
>> +		   gnus-extract-address-components
>> +		   (or (cdr (assq 'Newsgroups (mail-header-extra h1))) ""))))
>> +     (or (car extract) (cadr extract)))
>> +   (let ((extract (funcall
>> +		   gnus-extract-address-components
>> +		   (or (cdr (assq 'Newsgroups (mail-header-extra h2))) ""))))
>> +     (or (car extract) (cadr extract)))))
>
> I rewrote that to:
>
> (defun gnus-article-sort-by-newsgroups (h1 h2)
>   "Sort articles by newsgroups."
>   (let ((ex
>          (lambda (h)
>            (let ((extract
>                   (funcall gnus-extract-address-components
> 		           (or (cdr (assq 'Newsgroups (mail-header-extra h)))
>                                ""))))
>              (or (car extract) (cadr extract))))))
>     (gnus-string< (funcall ex h1) (funcall ex h2))))
>
> To avoid the duplication -- let me know if I messed up that bit.

Looks good, thank you!

I originally had duplicated that code from
`gnus-article-sort-by-recipient' and it's probably a good idea to make
that into a utility function.