From: Joe Van Dyk <joevandyk@...>
Date: 2005-12-13T13:57:07+09:00
Subject: Re: Accessing C structures in Ruby

On 12/12/05, Eero Saynatkari <ruby-forum-reg@mailinator.com> wrote:
> Joe Van Dyk wrote:
> > (I've already looked at Swig, btw.  I'd like to do this one by hand.)
> >
> > I have the following:
> >
> > typedef struct {
> >   double x;
> >   double y;
> >   double z;
> > } VelocityRecord;
> >
> > typedef struct {
> >   double x;
> >   double y;
> >   double z;
> > } PositionRecord;
> >
> > typedef struct {
> >   int id;
> >   int type;
> >   PositionRecord position;
> >   VelocityRecord velocity;
> > } Player;
> >
> > Player Players[10];
> >
> >
> > The number of Players is fixed ahead of time.  I want to be able to
> > access that data from Ruby.  Ideally, something like:
> >
> > module Simulation
> >     attr_accessor :players  # Other stuff will be here
> >     class Player
> >         class VelocityRecord
> >             attr_accessor :x, :y :z
> >         end
> >         class PositionRecord
> >           attr_accessor :x, :y, :z
> >         end
> >     end
> > end
>
> My typical recommendation is to just wrap a pointer to
> the struct and pass that around. Then, for each method
> just extract the pointer, access the correct field and
> generate a VALUE out of that (inside the function that
> corresponds to the method).

Can you share more details?  Is that essentially what I've done in my
later posts on this?