Salomon, see inline comments below.
HTH,
Chuck
> On Apr 10, 2020, at 7:56 AM, Salomon Turgman <sturg...@gmail.com> wrote:
>
> Hello all,
>
> Thanks in advance for any hints you can provide for this. I am trying to
> create a derived back-end that handles a new type of block in org-mode. I am
> trying to derive using the html export backend as a parent.
>
> Currently I am solving my problem like this:
> #+CAPTION[Manual control]: Simulation 1: Manual control of the tank level.
> #+BEGIN_EXPORT html
> <div class="caption">Simulation 1: Manual control of the tank level.</div>
> <div class="simulation">
> <div id="main1">
> <noscript>
> Some other cool stuff here.
> </noscript>
> </div>
> </div>
> <script>var app = Main1.init({node:
> document.getElementById("main1")});</script>
> #+END_EXPORT
>
> This has a few downsides:
> 1. I have to specify the caption twice since export translator does not
> handle captions.
> 2. I have to include substantial amounts of html.
> 3. I have keep track of references to simulations manually (simulation 1,
> simulation 2, etc)
> 4. I have to include the identifier `main1` or `Main1` in several locations
> in the snippet.
>
> I could solve some of this with an automated snippet insertion tool but I
> thought that maybe I can get the export back-end to do most of the work for
> me.
>
> So I am trying to derive as follows (in pseudo-elisp-code):
> (require 'ox)
> (require 'ox-html)
>
> (org-export-define-derived-backend 'textbook 'html
> :menu-entry
> '(?I "Export textbook section"
> ((?b "To buffer" org-html-export-as-html)
> (?I "To file" org-html-export-to-html)
> (?o "As HTML file and open"
> (lambda (a s v b)
> (if a (org-html-export-to-html t s v b)
> (org-open-file (org-html-export-to-html nil s v b)))))))
> :translate-alist '((simulation . org-textbook-simulation)))
>From the `org-export-define-backend' docstring:
"TRANSCODERS is an alist between object or element types and
functions handling them."
But `simulation' is not such a type. So, this will not work.
>
> (defun org-textbook-simulation (element contents info)
> (let* ((simnum (extract simnum value))
> (caption (org-export-get-caption element))
> (divid (extrac divid value))
> (modid (convert divid into modid))
> )
> (format "<div class=\"caption\">Simulation %simnum%: %Caption%.</div>
> <div class=\"simulation\">
> <div id=\"%divid%\">
> </div>
> </div>
> <script>var app = %modid%.init({node:
> document.getElementById(\"%divid%\")});</script>"
> simnum caption divid modid divid)))
>
> With the hope that I can do something like this in my .org file:
>
> #+CAPTION[Manual control]: Simulation 1: Manual control of the tank level.
> #+BEGIN_SIMULATION main1
> Some other cool stuff here
> #+END_SIMULATION
I think an easier approach is to write a babel src-block that formats the
inputs you need and creates a value that is your desired output.
Use `:var' header arguments to define the inputs.
Use `:wrap html' to prevent the exporter from changing the output.
Subsequent calls can use the `#+CALL' idiom.
You can use any scripting language that suits you - elisp, python, shell, R,
... --- for this purpose.
If you are skilled in emacs-lisp you might write an `eval' macro instead of a
src block.
>
> Am I on the right track here? Can someone point me to an example on how to:
> 1. Keep track of the number of simulations for referencing?
Using the babel approach, you would need a `:session' with a persistent
variable that would hold the count. You would need to initialize it in your
document so that subsequent exports will start counting at zero.
> 2. Extract the caption properly? The above is just my guess.
IIRC, the info channel is not populated when babel runs, so you will need to
parse the src-block and extract the `:caption' element. I think you can use a
`:var cap=(find-caption)' idiom, where `find-caption' is a function you write
using `org-element-context' as a starting point.
Or if the only need you have for the caption is within that src block just use
`:var cap="<your caption here>".
> 3. Extract the divid value (main1)
:var divid="main1"
> 4. And finally, how to get org to recognize the new SIMULATION block so that
> it can apply `org-textbook-simulation`? Do I need to register this type of
> block somewhere? Or is the name of the first member of the :translate-alist
> translation pair have some special meaning?
Don't go in that direction. Use babel or write an eval macro.
[snip]
