* [babel] ob-C.el annoyances
@ 2011-04-15 13:54 Julien Fantin
2011-04-15 16:24 ` Eric Schulte
0 siblings, 1 reply; 2+ messages in thread
From: Julien Fantin @ 2011-04-15 13:54 UTC (permalink / raw
To: emacs-orgmode
Hi list, hi Eric,
I've been using ob-C to go through the K&R book, and I've noticed a few
annoyances along the way.
* Use of the captial C identifier
Support functions are defined as ob-C-*. In consequence, I need to
#+begin_src C to get a block to execute, because #+begin_src c fails
with "No org-babel-execute function for c!". The problem is that I can't
edit the block since there is no C-mode. Defining an alias fixed the
issue, but it doesn't work OOTB, and doesn't feel like a good solution
at all.
Is there a reasoning behind this, or where you, as I suspect, trying to
define some support functions that would work for both C and C++ ?
* Feeding text into blocks
This is not directly related to ob-C.el, but I was looking for a way to
feed some text to a block's STDIN while it was executed by babel. I
wanted to specifiy this text either inline from the block's header
arguments or from a dedicated text block.
It'd ideally look like this :
** Inline
#+begin_src c :feed foo bar
int main(void) {
while ((c = getchar()) != EOF) {
putchar(c);
}
return 0;
}
#+end_src
#+results:
: foo bar
** From a text block
#+source: my-stdin
#+begin_src text
foo bar
#+end_src
#+begin_src c :feed my-stdin
int main(void) {
while ((c = getchar()) != EOF) {
putchar(c);
}
return 0;
}
#+end_src
#+results:
: foo bar
TL;DR if this is already possible somehow please skip the following and let
me know :)
I couldn't figure out how to pipe the text from within babel though. So
I resorted to tangling the text blocks, and redefined
org-babel-C-execute to use that new header argument :feed. It gets
prepended to the cmdline in the org-babel-eval function call ; if foo is
an existing file it gets cat'ed through a pipe to the rest of the
cmdline in org-babel-eval, otherwise it is simply echo'ed. This is not
as good as what I described above, but after getting to use it, I really
think a generalization of this use-case is desirable.
Please let me know whar you think.
Regards,
Julien.
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [babel] ob-C.el annoyances
2011-04-15 13:54 [babel] ob-C.el annoyances Julien Fantin
@ 2011-04-15 16:24 ` Eric Schulte
0 siblings, 0 replies; 2+ messages in thread
From: Eric Schulte @ 2011-04-15 16:24 UTC (permalink / raw
To: Julien Fantin; +Cc: emacs-orgmode
Julien Fantin <julienfantin@gmail.com> writes:
> Hi list, hi Eric,
>
> I've been using ob-C to go through the K&R book, and I've noticed a few
> annoyances along the way.
>
> * Use of the captial C identifier
>
> Support functions are defined as ob-C-*. In consequence, I need to
> #+begin_src C to get a block to execute, because #+begin_src c fails
> with "No org-babel-execute function for c!". The problem is that I can't
> edit the block since there is no C-mode. Defining an alias fixed the
> issue, but it doesn't work OOTB, and doesn't feel like a good solution
> at all.
>
I've changed the default value of `org-src-lang-modes' so with the
latest version of Org-mode the "begin_src C" code blocks will use the
appropriate mode without the need to define an alias. Thanks for
pointing out this inconsistency.
>
> Is there a reasoning behind this, or where you, as I suspect, trying to
> define some support functions that would work for both C and C++ ?
>
For a while we had a mix of both "C" and "c" in our function names, and
recently we normalized on "C". It seems we left a few loose ends in
this process.
>
>
> * Feeding text into blocks
>
> This is not directly related to ob-C.el, but I was looking for a way to
> feed some text to a block's STDIN while it was executed by babel. I
> wanted to specifiy this text either inline from the block's header
> arguments or from a dedicated text block.
>
There is currently the option of passing command line arguments to C
code blocks, e.g.,
#+begin_src C :cmdline 1 2 3 4 5 :includes <stdio.h>
int main(int argc, char **argv){
printf("argv[1] %s\n", argv[1]);
return 0;
}
#+end_src
#+results:
: argv[1] 1
However there is no support for piping to/from the STDIN/STDOUT/STDERR
of code blocks. The issue of pipes has come up before (for example with
a robust piping interface, we could stream data between code blocks in
much the same way as piped commands on the command line). Such a change
would require significant work, may require support for asynchronous
code block execution.
While such large projects may make (for example) a good google SOC
project, I don't believe they will be implemented in the near future.
>
> It'd ideally look like this :
>
> ** Inline
>
> #+begin_src c :feed foo bar
> int main(void) {
> while ((c = getchar()) != EOF) {
> putchar(c);
> }
> return 0;
> }
> #+end_src
>
> #+results:
> : foo bar
>
> ** From a text block
>
> #+source: my-stdin
> #+begin_src text
> foo bar
> #+end_src
>
> #+begin_src c :feed my-stdin
> int main(void) {
> while ((c = getchar()) != EOF) {
> putchar(c);
> }
> return 0;
> }
> #+end_src
>
> #+results:
> : foo bar
>
> TL;DR if this is already possible somehow please skip the following and let
> me know :)
>
> I couldn't figure out how to pipe the text from within babel though. So
> I resorted to tangling the text blocks, and redefined
> org-babel-C-execute to use that new header argument :feed. It gets
> prepended to the cmdline in the org-babel-eval function call ; if foo is
> an existing file it gets cat'ed through a pipe to the rest of the
> cmdline in org-babel-eval, otherwise it is simply echo'ed. This is not
> as good as what I described above, but after getting to use it, I really
> think a generalization of this use-case is desirable.
>
> Please let me know whar you think.
>
I agree fully, however I would want to implement piping in such a manner
that it can easily be extended to any language, rather than in a C
specific manner. It sounds like you have a nice solution currently.
Perhaps rather than overwriting the execute function, you could wrap
this up into a new function, and share the code on Worg so others could
incorporate it into their workflow.
Best -- Eric
>
> Regards,
> Julien.
>
>
>
--
Eric Schulte
http://cs.unm.edu/~eschulte/
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