[babel] ob-C.el annoyances

[Julien Fantin <julienfantin@gmail.com>]

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.