[Chicken-users] SWIG and c-callback with arguments

[Bastian Müller]

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Hi,

I'm currently trying to get an interface to the Open Dynamics Engine
with SWIG.

typedef void dNearCallback (void *data, dGeomID o1, dGeomID o2);
void dSpaceCollide (dSpaceID space, void *data, dNearCallback  
*callback);

I saw that the glib egg is able to do callbacks using the following  
code:

%{
static void
EGG_signal_handle ( gpointer *obj, gpointer closure_root )
{
  C_callback(CHICKEN_gc_root_ref(closure_root), 0);
}
%}

%inline %{
gulong
EGG_g_signal_connect (gpointer obj, const gchar *type, C_word closure)
{
  void *closure_root = CHICKEN_new_gc_root();
  CHICKEN_gc_root_set(closure_root, closure);
  return g_signal_connect(G_OBJECT(obj), type, G_CALLBACK 
(EGG_signal_handle), closure_root);
}
%}

It seems to work fine, so I copied it and slightly modified it for ODE:

%{
static void
EGG_near_callback (void *closure_root, dGeomID o1, dGeomID o2) {
  C_callback(CHICKEN_gc_root_ref(closure_root), 0);
}
%}

%inline %{
void
EGG_dSpaceCollide (dSpaceID space, C_word closure)
{
  void *closure_root = CHICKEN_new_gc_root();
  CHICKEN_gc_root_set(closure_root, closure);
  return dSpaceCollide(space, closure_root,  EGG_near_callback);
}

Then I noticed that glib's callback doesn't have any arguments, so
I changed it to:

 C_callback(CHICKEN_gc_root_ref(closure_root), 2);

But even with that, the arguments I get in the actual scheme-callback
are wrong. I looked and searched for some documentation and stumbled
across C_save:
C_save(o1);
C_save(o2);
C_callback(CHICKEN_gc_root_ref(closure_root), 2);

Still, the code doesn't work with callback arguments.
It would be very cool if somebody with more knowledge
about scheme, chicken and swig could have a look at this.

Thanks in advance
- --
Bastian Müller - http://turbolent.com/


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