Babel questions for finalising Processing support

[Jarmo Hurri <jarmo.hurri@iki.fi>]

Greetings.

My implementation of Processing support in Babel is proceeding really
well! I have now both external viewing of sketches and export to html
(sketches drawn by browser) working.

There are a number of details to fix, though.

1. When editing Processing code with C-c ' I get an error from
   processing-mode. Editing with C-c ' works just fine, but the error is
   annoying. It seems to me the error is caused by the fact that
   processing-mode refers to buffer-file-name, which is not valid in a
   temporary buffer. Any ideas on how to fix this inside org? (Wouldn't
   want to get involved with processing-mode if it can be avoided.) Is
   there for example a hook I could use to set buffer-file-name to some
   temporary value?

2. When processing code is executed with C-c C-c, it shows the sketch in
   an external viewer. When exported, the results are html code. To this
   end I have set default header arguments for Processing to be
   ":results html" and ":exports results". With C-c C-c execution,
   org-babel-execute:processing returns nil.

   This works fine otherwise, but even C-c C-c execution produces an
   empty results section:

   #+RESULTS:
   #+BEGIN_HTML
   #+END_HTML

   This is a nuisance, since C-c C-c execution always also changes the
   current file (even though nothing changes). Is there a way to avoid
   this?
   
3. In ob-processing.el I (require 'ob). However, to avoid a compiler
   warning about a free variable I still need to declare

   (eval-when-compile (defvar org-babel-temporary-directory))

   Is this ok?

4. Processing support in Babel will depend on processing2-emacs module,
   which contains the function processing-sketch-run. Again, to avoid
   compiler warnings, I am declaring this by

   (declare-function processing-sketch-run "processing-mode.el" nil)

   Is this ok?

Jarmo