Re: [Babel] No output returned if just one command is failing

From: "Sébastien Vauban" <wxhgmqzgwmuf-geNee64TY+gS+FvcfC7Uqw@public.gmane.org>
To: emacs-orgmode-mXXj517/zsQ@public.gmane.org
Subject: Re: [Babel] No output returned if just one command is failing
Date: Thu, 02 Dec 2010 21:27:31 +0100	[thread overview]
Message-ID: <80fwufudho.fsf@missioncriticalit.com> (raw)
In-Reply-To: 87sjygf3ym.fsf@gmail.com

Hi Dan and Eric,

Dan Davison wrote:
> Sébastien Vauban writes:
>> Dan Davison wrote:
>>> Sébastien Vauban wrote:
>>>> "Eric Schulte" wrote:
>>>>> I don't forsee adding partial results insertion both because
>>>>>
>>>>> - it would add a good deal of complexity to the code to insert results
>>>>>   part-way through a run
>>>>
>>>> I can't comment on this, of course.
>>>>
>>>>> - the current behavior of only inserting results on a fully successful run
>>>>>   is reasonable and is probably more obvious (at least to me) than
>>>>>   inserting partial results
>>>>
>>>> Being fond of Babel, I'm using it always, everywhere. I prefer:
>>>>
>>>> 1. typing my shell commands in an Org buffer,
>>>> 2. evaluate the block,
>>>> 3. get the results automagically inserted in the buffer,
>>>> 4. (eventually, version the whole file for later comparisons when updating
>>>>    the code),
>>>> 5. export the whole to HTML and/or PDF.
>>>>
>>>> The current behavior, even if totally respectable and defendable, inhibits
>>>> such a way of working: if you write (or update) a shell code, and don't see
>>>> (more or less) the same things as the ones you would see in a shell buffer,
>>>> then you can't use such an Org buffer -- as long as one command fails.
>>>>
>>>> I don't especially want you to change your position, but I'm explaining the
>>>> "negative" consequences for me.
>>>
>>> I definitely have some sympathy with your request. On two occasions I've had
>>> to manually make this change just to carry on working.
>>>
>>> But do we actually change babel in this direction? [...]
>>>
>>> The thing is that babel currently has a clear, simple, rule which says: if
>>> there's an error, the result is the elisp value nil.
>>>
>>> Eric and I have discussed in the past whether there should be any change
>>> in this direction. The idea of a :debug header arg has been floated,
>>> that would allow this behavior. Or tacking stdout on to the error
>>> output. I tend to think that the behavior you request does need to be
>>> made available, somehow, whether by default or not.
>>
>> If find this conclusion a bit contradictory with the fact that you even needed
>> it yourself.
>
> Hey Seb -- you mis-read me there. I was agreeing with you that the
> behavior should be made available.

Yes, it seems I did add a implicit *not* in your last sentence...

My impressions are that shell blocks may be a totally different beast from the
other source blocks. If so, it could legitimate a slightly different treatment
(or default set of options).

All of this discussion once again turns around the handling of errors, and the
two streams (stdout and stderr). Aaaah, here's well a proof it's different
from the rest (languages such as emacs-lisp), at least in their classic usage?

My dream would be to be able to write, debug and use code blocks from Org, and
only Org. Not be forced to use the shell because some unknown condition make
them return an error.

    Note: Can you explain me what's an error in the case of a sh block?  See
    my previous post(s) of today. Thanks...

Maybe once acceptable solution would be to output everything as it is in the
terminal, mixing both streams.

A possible dream of mine could maybe even become true here: the possibility to
clearly distinguish both streams by coloring them differently in the Org
results: for example, all lines from stdout in black, all lines from stderr in
red...

Though, I understand Eric's fears of problems for chained blocks execution.
But, anyway, what else would you expect than what occurs in a terminal?  Why
should it be different?

Best regards,
  Seb

-- 
Sébastien Vauban

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