passing a reference to a primitive?

I've been working through some of the examples and I can't figure out
what's wrong.

I have a function that takes a reference to a double:

  void fn(double& value) {
    value += 3.4;
  }

I bind it with code that looks something like:

  module(L) [
    def("fn", fn)
  ]:

Then try to run it:
 
  luaL_dostring(
    L,
    "fval = 3.2\n"
    "fn(fval)\n"
  );

I get back an error that says something like:

  No matching overload found, candidates:
  void fn(custom [double]&)

I've tried being super-specific by binding fn like this:

  def("fn", (void(*)(double&)fn)

but I get the same result. I'm really trying to use the out_value
policy, but I can't even get this to compile:

  def("fn", fn, out_value(_1))

FWIW, I'm using VS2010.

I'm starting to wonder if I should just stick to the Lua's C api and try
to keep my dependencies to a minimum. Frankly, when I try to figure out
how luabind is working, it pretty much looks like magic.

The canonical version of luabind doesn't appear to be maintained any
more. I know some people on this list are maintaining forks and I'm
wondering if their version of luabind works for what I'm trying to do?
I've started to play with boost-python. It seems much heavier and more
complicated, but also more active.

Advice and suggestions welcomed!

Thanks,
Cory



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