[PATCH] emacs: hello: make --batch error gracefully

[Tomi Ollila]

On Fri, Jul 05 2013, Mark Walters <markwalters1009 at gmail.com> wrote:

> Recently notmuch-hello was converted to use batch count. However, it
> seems that several people run different versions of notmuch-emacs and
> notmuch-cli so this batch makes emacs fail with an error message if
> --batch is not available in the CLI.
> ---
> There have been two cases on irc of people getting backtraces when
> hitting this problem so it might be worth adding an informative error
> message.

This change takes care of the mismatching version problem now -- for
a short while in most cases but in the future we might face with new
incompabilities that would -- again -- need new solution. Some day
we might have a pile of these who everyone is shy to remove from the
code base ;/

Although I am not against applying this patch (if there are supporters
of this) I'd like to concentrate fixing this for example the following
way:

We'll add a global option to notmuch, e.g.

--compatibility-version=x.y

Whenever the caller chooses to use this option, notmuch checks whether
it can comply with the option -- it it can, execution continues, otherwise 
aborts.

The compatibility is determined so that the major 'x' needs to be same
and caller may have lower 'y' that notmuch is capable of handling.

For example. if notmuch compatibility version was 2.5

--compatibility-version=1.9  --  abort
--compatibility-version=2.3  --  continue
--compatibility-version=2.5  --  continue
--compatibility-version=2.8  --  abort
--compatibility-version=3.1  --  abort


I can work on this (or on something similar) if this is generally thought
as a good idea...

>
> Best wishes
>
> Mark

Tomi


>
>  emacs/notmuch-hello.el |    9 +++++++--
>  1 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/emacs/notmuch-hello.el b/emacs/notmuch-hello.el
> index 147c08c..fa46b7a 100644
> --- a/emacs/notmuch-hello.el
> +++ b/emacs/notmuch-hello.el
> @@ -402,8 +402,13 @@ options will be handled as specified for
>  					   (plist-get options :filter)))
>  	 "\n")))
>  
> -    (call-process-region (point-min) (point-max) notmuch-command
> -			 t t nil "count" "--batch")
> +    (unless (= (call-process-region (point-min) (point-max) notmuch-command
> +				    t t nil "count" "--batch") 0)
> +      (notmuch-logged-error "notmuch CLI version mismatch error (count --batch)
> +The most likely cause of this error is that the CLI is too old
> +to support count --batch and needs to be upgraded to the same
> +version as notmuch-emacs"))
> +
>      (goto-char (point-min))
>  
>      (notmuch-remove-if-not
> -- 
> 1.7.9.1
>
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