From: Jason Roelofs <jameskilton@...>
Date: 2007-12-25T04:02:38+09:00
Subject: C++ Functors and Ruby extensions

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I wonder if anyone has tried to do what I'm doing and if they've come up
with an appropriate solution.

Basic idea:

struct ruby_func_wrapper
{
   VALUE operator()(VALUE self, VALUE args)
   {
       m_callback(args ...);
   }
}

extern "C"
void Init_functor_test() {
   ruby_func_wrapper functor;
   [ ... code that sets callback of functor ... ]

   rb_define_global_function("functor_test", [something here &functor], -2);
}

Basically, I want to use instances of the ruby_func_wrapper functor as
callback for Ruby methods. I'm using Boost right now, and have tried
Boost.Function and Boost.Bind to no avail (the code compiles but the actual
call causes a seg fault, I assume the memory location is voided after the
init is done, so trying to pass execution to a bad memory location, but I'm
not sure). For the record, I am trying my hand at a Boost.Ruby library.

I'm also wondering if there is another way to add methods to Kernel or
Classes outside of the rb_define_* methods. In Python you can do
PyObject_SetAttr(namespace, name, PyCFunction) which is effectively ("
namespace.name = function"). I've yet to find an equivalent in Ruby.

I hope this is clear, though if not I can post the full code I've got right
now.

Thanks

Jason

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