#+title: Add links to code block during orgmode export
#+date: [2020-02-29 Sat]
#+author: Yann Esposito
#+EMAIL: yann@esposito.host
#+keywords: org-mode blog
#+DESCRIPTION: Add links to code block during orgmode export.
#+OPTIONS: auto-id:t toc:t
#+STARTUP: overview

I wanted to add a link to the file I export with org tangle.
And it was surprisingly difficult to find.
Apparently I am one of the few people that use orgmode the way I do.

Using orgmode file as markdown to blog.
And exporting to a different file some code block.
So I often endup writing something like:

#+begin_src org
..begin_src elisp :tangle foo.el
#+end_src

I tangle the source code that export the code block to an external file.
Then I use this hook during HTML export to add a caption with the link the
file I tangled:

#+begin_src elisp :tangle org_html_export_show_tangle.el
(defun my-add-link-to-tangled-files (backend)
  "Add a link just before source code block with tangled files.
BACKEND is the export backend. Used as symbol."
  (while ;; (re-search-forward )
      (re-search-forward "^\\( *\\)#\\+begin_src .*:tangle \\([^\s\n]*\\)" nil t)
    (replace-match "\\1#+CAPTION: [[./\\2][=\\2=]]\n\\&")))

(add-hook 'org-export-before-processing-hook
          'my-add-link-to-tangled-files)
#+end_src

And this article is an example of the result.
The link with the listing is generated automatically for me.

A small note regarding CSS.
My =pre= have a =margin-top=.
But I wanted to get rid of it when the previous block was a =label=.
This is achievable with:

#+begin_src css
label + pre {margin-top: 0;}
#+end_src

That's it.
It took me really a long time to just think about using caption, and not
trying something smarter like injecting html code, etc...
So I hope it could help someone.