Can LuaCoco yield from outside of a Lua C Function?

[mitchell <code@...>]

Hi,

I am running a Ruby interpreter and the Lua interpreter within a single 
application and I was wondering if I can call lua_yield() from within a 
Ruby function using LuaCoco. So far I'm getting the usual "attempt to 
yield across C-boundary" error, but my implementation might be erroneous. 
Here's a quick overview of the code:

-- Lua code
co = coroutine.create(function()
  run_ruby() // calls the c function below
  print('done')
end)
value = coroutine.resume(co)

----------

// Lua C function
static int run_ruby(lua_State *L) {
  ruby_init_stuff();
  rb_define_global_function("lua_yield", l_yield, 1); // l_yield is below
  ruby_run(some_script) // where some_script calls "lua_yield"
  return 0;
}

// Ruby function
static VALUE l_yield(VALUE self, VALUE arg) {
  lua_pushsomething(L, RUBY2LUA(arg));
  lua_yield(L, 1); // coroutine.resume() should return the arg
  printf("This should not be called right away due to lua_yield()\n");
  ...
}

----------

Thanks for any pointers.

mitchell