Re: [BUG] on export resulting in endless evaluation

[Charles Berry <ccberry@ucsd.edu>]

Rainer M Krug <Rainer <at> krugs.de> writes:

> 
> Sebastien Vauban <sva-news@...>
> writes:
> 
> > Rainer M Krug wrote:
> >> Charles Berry <ccberry@...> writes:
> >>> Rainer M Krug <Rainer <at> krugs.de> writes:
> >>>> 
> >>>> when exporting the fillowing org file, I get an endless loop of
> >>>> evaluations.
> >>>> 
> >>>> --8<---------------cut here---------------start------------->8---
> >>>> #+PROPERTY: header-args :exports both
> >>>> #+PROPERTY: header-args+ :results output
> >>>> * The bug
> >>>> This file create an (possibly endless?) loop during export
> >>>> * here exports both
> >>>> #+begin_src R 
> >>>> cat(13+14)
> >>>> #+end_src
> >>>> 
> >>>> * and here only code
> >>>> :PROPERTIES:
> >>>> :header-args+: exports code
> >>>> :END:
> >>>> #+begin_src R 
> >>>> paste(13+14)
> >>>> #+end_src
> >>>> --8<---------------cut here---------------end--------------->8---
> >>>

[discussion of problem, diagnostic methods, and cures deleted]


> 1) I thought that header-args is simply a string, but it already seems
> to be a list?

Depends on which `header-args' one is discussing:

1. A property, as in `(org-entry-get (point) "header-args" t)'

2. The value of `(nth 2 (org-babel-get-src-block-info))'

3. The value of an elisp variable like `org-babel-default-header-args'

4. The 4th string matched by `org-babel-src-block-regexp' 

5. The first string matched by `org-babel-multi-line-header-regexp'

1, 4 and 5 are strings. 2 and 3 are lists.

> 
[more questions deleted]
> 

Exactly what happens and when is a long story, involving a bunch of 
functions.

You might start by reading `org-babel-get-src-block-info' and 
`org-babel-merge-params'.

I think most of what you need to know really is in 

   (info "(org) Using header arguments")
and
   (info "(org) Property syntax")

Just remember that a property called `header-args' is a string until Babel 
starts working on it.


> 5) Is there any way in getting, in this function, the same output
> (header-args) as from the code block suggested by Charles:
> 

You might try

#+BEGIN_SRC emacs-lisp :results pp
   (cons (org-entry-get (point) "header-args" t)
         (nth 2 (org-babel-get-src-block-info)))
#+END_SRC

HTH,

Chuck