Thank you very much. I will explore what you suggest. I'm glad I emailed,
seems like I was going down the wrong path.

Salomon

On Fri, Apr 10, 2020, 1:10 PM Berry, Charles <ccberry@health.ucsd.edu>
wrote:

> Salomon, see inline comments below.
>
> HTH,
>
> Chuck
>
> > On Apr 10, 2020, at 7:56 AM, Salomon Turgman <sturgman@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]
>