Re: Include sections of org document in tangled files

["Charles C. Berry" <ccberry@ucsd.edu>]

On Wed, 7 Dec 2016, David Dynerman wrote:

> Dear Chuck,
>
> Your suggestion worked fantastically - I got it working and am very excited.
>
> Now, the next step is figuring out how to handle typesetting math in single way between org and python docstrings. Math in Python docstrings is usually done by RestructuredText markdown, e.g.:
>
> :math:`f(x) = x^2`
>
> while the org code should just be, for example,
>
> \[
> f(x) = x^2
> \]
>

> So the goal would be have noweb not only include a documentation block 
> in the python code, but also call a translation function that identifies 
> LaTeX fragments in the org source and converts them to ReST markdown.
>

This is do-able.

First, look at

 	(info "(org) Noweb reference syntax")

and note that the noweb reference

 	<<my-src-block(x="value_for_x")>>

will call `my-src-block' with the `x' var set to "value_for_x" and insert 
the output into the current src block.

Second, https://github.com/masayuko/ox-rst has a reStructuredText backend. 
So, you can install ox-rst.el, then write an emacs-lisp src block:


#+NAME: export-body
#+BEGIN_SRC emacs-lisp :var src-block-name="my-code" :results raw
   (save-excursion
     (org-babel-goto-named-src-block
      src-block-name)
     (org-export-string-as
      (org-babel-expand-src-block)
      'rst t))
#+END_SRC

and then a src-block like this

#+BEGIN_SRC emacs-lisp :noweb yes :tangle yes
<<export-body("my-code")>>
#+END_SRC

will insert the rst formatted text from the `my-code' src block when the 
latter src block is tangled.

p.s. Untested with 'rst.

HTH,

Chuck