[PATCH v2] emacs: Report a lack of matches when calling `notmuch-show'.

[David Edmondson]

On Wed, Feb 10 2016, Mark Walters wrote:
> This basically looks fine to me and all tests pass. The code movement
> and cleanup all looks fine.

Thanks.

> Two minor things, one tiny nit below; and I wonder whether just having
> the buffer say "No search results" (or something similar) and leave
> the user to kill it would be nicer than dinging (and more in line with
> the way search and tree behave).
>
> [In some sense I think this way is right and search and tree are wrong,
> but that is probably difficult to get round as search and tree run
> asynchronously.]

What if we did "notmuch count $query" first in the search and tree case,
and did the "(ding) (message ...)" thing if the count returned 0? (Just
wondering about whether having everything behave that way would be
possible and acceptable.)

The original impetus for this change was someone who hits an id: button
that is either a false match (i.e it wasn't ever intended to be a
notmuch reference) or for a message that they don't have. In both of
those cases popping up a buffer that says only "No match." would be
annoying. If we were considering the case where people are using "M-x
notmuch-show", it seems less clear on the right thing to do, but overall
I prefer this approach to the useless buffer that I have to kill/quit.

>> +      ;; Cache the original tags for each message so that we can display
>> +      ;; changes.
>
> ^^ I think "Store the original tags for each message" would be better,
> particularly as this is nothing to do with the tag cache as used by say
> notmuch-tag-clear-cache.

Agreed - fixed.