Re: [Guidolib-devel] Guido.js: A JavaScript Port of Guido

[Alexander D. <al...@mu...>]

Bonjour Dominique!

It is a pleasure to correspond with you, I really admire your work on
Guido.  And other projects too! I actually just sent the INScore demo video
to a friend, who thought it was great.

I'll respond in-line.

> Concerning the web, there is already an approach that should be published
soon :  a restful web service embedding the guido
> engine and providing the guido library API over http.

Cool! I think this could be a nice service. Sounds like it will be a nice
evolution of the original NoteServer project.

> Could you tell what is your approach ? Rewriting the engine in javascript
? automatically converting the C++ code in javascript (as > much as
possible) ? a mix of both ?

My approach is to rewrite the engine in Javascript. Currently I have ported
the parser and a few of the AR classes:
https://github.com/musikata/guido.js/tree/master/src .

I prefer this approach to compiling c++ to JS fro two main reasons: (1)
File Size, and (2) Flexibility

= 1. File Size =
JS code generated by C/C++ => JS tools like Emscripten can be quite large.
Too large for reasonable performance on mobile devices.

Initially I had tried using Emscripten to compile the GuidoEngine code into
JS. With some tweaking (taking out dependencies on external libs like
Cairo), I was successful in doing this. I was able to make 'JsSystem' class
in C++ that acted as a bridge between the C++ scope, and the javascript
scope, and was able to emit a stream of Guido graphic commands to the
javascript console.

However, the resulting code was quite large. After minification, it was
about 2.2 MB. After minification + gzip (what the browser would actually
need to transfer over the wire) it was about 460 KB. N'est-ce pas un peu
gros, no? ;)

But despair not, I think there is hope.

I think it will be possible to get hand-written JS code down to at least
400KB.

This estimate is based on the classes that I have ported so far; As
un-minified JS files, they are 50% - 75% of the size of their C++
counterparts. The combined size of the GuidoEngine .cpp files in src/ is
about 2.3 MB. I think I can get this down to 1 MB. Then minification can
reduce this to 400 KB or less.  Which should gzip to 100 KB or less. Plus
délicieux!

= 2. Flexibility =
I also prefer re-writing in javascript because it offers more flexibility.

With the compilation approach, we would need to do these things to make a
change:
- 1. Edit the C++ code
- 2. Re-compile the C++ into JS
- 3. Test in JS

Un peu énervant, eh?

Whereas with re-written JS, we can test in JS, and also debug in JS.

Peut-être je suis trop prolix maintenant.

== The Downside ==
The downside of the hand-written approach is that it will take time.
Nothing good comes without work.

I hope I can rally some development efforts around it.


> Do your plan to use javascript as is, or a derived typed lang like
TypeScript ( http://www.typescriptlang.org/ ) ?

I plan to use plain javascript, organized as AMD modules.  I thought about
using TypeScript or CoffeeScript, but I personally find plain JavaScript
more readable. Call me old-fashioned I guess.

> Anyway your project is really interesting and I hope we'll be able to
join our efforts.

Me too! I hope it becomes something that helps all of our projects. You
your team have already helped mine with all your work on Guido!

== Other Hopes ==
My hope is that Guido can be helpful for other javascript tools too. I have
a friend who is working on in-browser synthesis tools (
http://flockingjs.org/ ). He may be interested in a musical encoding system
for his project. Guido seems like an excellent candidate.

I think there are some really exciting possibilities for Guido in the
future. And I'm sure you have already thought of many of them!

> ps: and I wish you a quick thaw :-)

Merci! Et a vous aussi. Ici c'est plus froid que l'amour que un développeur
web a pour IE6 ;)

-Alex

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