[PATCH] Avoid empty thread names if possible.

[Mark Walters]

Hi

On Tue, 07 Oct 2014, Jesse Rosenthal <jrosenthal at jhu.edu> wrote:
> Currently the thread is named based on either the oldest or newest
> matching message (depending on the search order). If this message has
> an empty subject, though, the thread will show up with an empty
> subject in the search results. (See the thread starting with
> `id:1412371140-21051-1-git-send-email-david at tethera.net` for an
> example.)
>
> This patch changes the behavior to name based on the oldest/newest
> matching non-empty subject. This is particularly helpful for patchsets.
> If the only subjects are empty, the thread subject will still be empty.

I approve of the change in the output but I am unsure about the
implementation. It would be nice to have a clear rule about which
subject is taken. Eg: 

        if sort is oldest first then it is the subject of the oldest
        matching message with a non-empty subject. Similarly if sort
        is newest first.

Also, it would be nice if the implementation did not rely on what order
we call _thread_add_matched_message on the matching messages in the
thread. I think in some ways we already rely on the order (for the order
of the author list), but if you want to rely on the order here I think
it at least deserves a comment.

>
> Signed-off-by: Jesse Rosenthal <jrosenthal at jhu.edu>
> ---
>  lib/thread.cc | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/lib/thread.cc b/lib/thread.cc
> index 8922403..ea10295 100644
> --- a/lib/thread.cc
> +++ b/lib/thread.cc
> @@ -348,18 +348,20 @@ _thread_add_matched_message (notmuch_thread_t *thread,
>  {
>      time_t date;
>      notmuch_message_t *hashed_message;
> +    const char *cur_subject;
>  
>      date = notmuch_message_get_date (message);
> +    cur_subject = notmuch_thread_get_subject (thread);
>  
>      if (date < thread->oldest || ! thread->matched_messages) {
>  	thread->oldest = date;
> -	if (sort == NOTMUCH_SORT_OLDEST_FIRST)
> +	if (sort == NOTMUCH_SORT_OLDEST_FIRST || strlen(cur_subject) == 0)
>  	    _thread_set_subject_from_message (thread, message);
>      }
>  
>      if (date > thread->newest || ! thread->matched_messages) {
>  	thread->newest = date;
> -	if (sort != NOTMUCH_SORT_OLDEST_FIRST)
> +	if (sort != NOTMUCH_SORT_OLDEST_FIRST || strlen(cur_subject) == 0)
>  	    _thread_set_subject_from_message (thread, message);
>      }

So looking at the above I think the oldest first gives the subject in
my suggestion above (since the messages are supplied in oldest first
order). But newest first may not: indeed if the subject starts out as
something and becomes empty then this will set the subject empty and
then leave it empty.

(Note _thread_set_subject_from_message calls notmuch_message_get_header
which returns an empty string "" if the subject line is empty or not
present).

Best wishes

Mark


>  
> -- 
> 2.1.2
>
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