From: Jamis Buck <jgb3@...>
Date: 2004-10-29T00:30:30+09:00
Subject: Re: Ruby/DL (was Re: The real Ruby vs. Python.)

Michael DeHaan wrote:
> Speaking of Ruby/DL, I have a question ...
> 
> Supposing I have a library that demands control of an event loop.  
> Examples could include GLUT (glutMainLoop) or SDL, but maybe it's
> something else.    What ways are there in Ruby/DL to call back into
> Ruby code from the C library?

Ruby/DL does support callbacks, but only a fixed number of them (10, by 
default, unless you compile the DL extension yourself and specify 
otherwise):

   module Stuff
     extend DL::Importable
     dlload "..."

     extern "int fn_with_cb( void* )"

     def my_callback( x, y, z )
       do_something_with( x, y, z )
     end

     CALLBACK = callback( "int my_callback( int x, int y, int z )" )
   end

   Stuff.fn_with_cb( Stuff::CALLBACK )

There is an example in the libc.rb file in the sample subdirectory of 
the DL directory in the Ruby source distribution.

- Jamis

> 
> Is this even possible, or do I have to write Swig/XS for this?   Up
> until this point I haven't had a need for XS/Swig, so I've typically
> gone the Ruby/DL route (in what few Ruby apps I've written), or I've
> used Inline::C (awesome module, BTW) in Perl.
> 
> Anyhow, ruby-sdl and ruby-opengl may exist, but occasionally I take
> some pleasure in reinventing wheels...or at least in knowing how to.  
> In fact, ruby-opengl might be a good example after all.    I'd really
> like to stay down in C code for longer lengths of time, so this is a
> case where writing one's own bindings may be useful.
> 
> --Michael DeHaan
> 
> On Thu, 28 Oct 2004 07:49:01 +0900, gabriele renzi
> <rff_rff@remove-yahoo.it> wrote:
> 
>>Jamis Buck ha scritto:
>>
>>
>>
>>>Besides which: Ruby/DL is often touted as a great way to write extension
>>>libraries. Are there any examples of libraries that have been written
>>>using Ruby/DL instead of C? I've never seen any, much to my own
>>>frustration when I would like a good example of Ruby/DL usage. :(
>>>
>>
>>well I can only remember the htmltidy library, never looked at it, anyway :/
>>
>>
> 
> 
> .
> 


-- 
Jamis Buck
jgb3@email.byu.edu
http://www.jamisbuck.org/jamis