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

[Dan Davison <dandavison7@gmail.com>]

Hi Seb, I definitely have some sympathy with your request. On two
occasions I've had to manually make this change just to carry on
working. The change I made is straightforward if you need it as a
temporary hack:

--8<---------------cut here---------------start------------->8---
diff --git a/lisp/ob-eval.el b/lisp/ob-eval.el
index 8832d91..1cce003 100644
--- a/lisp/ob-eval.el
+++ b/lisp/ob-eval.el
@@ -57,7 +57,7 @@ STDERR with `org-babel-eval-error-notify'."
          (progn
            (with-current-buffer err-buff
              (org-babel-eval-error-notify exit-code (buffer-string)))
-           nil)
+           (buffer-string))
        (buffer-string)))))
 
 (defun org-babel-eval-read-file (file)
--8<---------------cut here---------------end--------------->8---

But do we actually change babel in this direction? It's important to
distinguish between :results output and :results value here. The change
that seems superficially attractive is to allow :results output to
output the contents of standard output, even if there has been an
error. After all, stdout might contain some useful data, and currently
babel refuses point blank to give it to you if there's been an
error. And as you say, this is the behavior we are used to in the
shell. This hypothetical change would leave the default :results value
alone (so the above patch would need modification).

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.

Dan

Sébastien Vauban <wxhgmqzgwmuf-geNee64TY+gS+FvcfC7Uqw@public.gmane.org>
writes:

> Hi Eric,
>
> "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.
>
> Thanks!
>
> Best regards,
>   Seb