From: Tomi Ollila <tomi.ollila@iki.fi>
To: Mark Walters <markwalters1009@gmail.com>, notmuch@notmuchmail.org
Subject: Re: [PATCH] emacs: hello: make --batch error gracefully
In-Reply-To: <87wqp2d618.fsf@qmul.ac.uk>
References: <1372976299-30389-1-git-send-email-markwalters1009@gmail.com>
	<m2mwq0t5v5.fsf@guru.guru-group.fi> <87wqp2d618.fsf@qmul.ac.uk>
User-Agent: Notmuch/0.15.2+193~g7350bd4 (http://notmuchmail.org) Emacs/24.3.1
	(x86_64-unknown-linux-gnu)
Date: Sat, 13 Jul 2013 11:06:44 +0300
Message-ID: <m2y59ag9yj.fsf@guru.guru-group.fi>
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On Sun, Jul 07 2013, Mark Walters <markwalters1009@gmail.com> wrote:

> Hi
> Tomi Ollila <tomi.ollila@iki.fi> writes:
>
>> On Fri, Jul 05 2013, Mark Walters <markwalters1009@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 ;/
>
> I think we want the unless clause anyway: we do not want to try parsing
> something and getting stacktrace errors whatever happens. The error
> message will need updating so I should probably add a FIXME to the
> code. Perhaps the patch roughly as is could be applied to 0.16 and the
> fixed error message together with your ideas from below to master?

Like said below (even) the current ok by me -- just that whatever is
chosen will be there into foreseeable future... ;)

>> 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:
>
> This looks good. Some thoughts below.
>
>> 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.
>
> I think the return value could indicate what the problem was (ie too new
> or too old): so frontends could decide to work around it (perhaps 22 and
> 23 to come after the format-version return values). This would mean that
> callers would have an easier way of telling if --compatability-version
> is supported at all to ease the transition.
>
> I wondered whether it overlapped with Austin's format-version stuff but
> I think it is sufficiently different but some clear documentation as to
> which means what could be helpful.

Yes, I had Austin's format-version options into mind when quickly drafting
the suggestion (we'd use the same 21&22 (or whatever) return values too...)

Now that I spend a week with only N9 as a computing device I've also
thought how much of a maintenance burden we want to take with this...
... and thought as an alternative that during byte compilation of emacs
files we pick notmuch cli version to the .elc files -- and just popup
a warning message (on first notmuch-hello invocation) if the versions 
differ...

I'll investigate what kind of emacs macro functionality could be used
to do this (more fun than solving sudoku's that is :D)

> Best wishes
>
> Mark

Tomi


>
>> 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
>>>
>>> _______________________________________________
>>> notmuch mailing list
>>> notmuch@notmuchmail.org
>>> http://notmuchmail.org/mailman/listinfo/notmuch
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