Re: Passing values by reference?

[Tobias Käs <tobias.kaes@...>]

Tables and Userdata are passed by reference, so you can use it to your
advantage, by wrapping the actual values in a Table or Userdata. Most times
Tables are best (at least for me) since you can wrap all variables of a
group in the same table.

----- Original Message ----- 
From: "Sacha Varma" <sacha@ssl.co.uk>
To: <lua@bazar2.conectiva.com.br>
Sent: Monday, June 16, 2003 12:03 AM
Subject: Passing values by reference?


>
> Can arguments and return values be passed by reference?
>
> I'm trying to work out how I would bind the following C function:
>
>   int * inc (int *p)
>   {
>     (*p)++;
>     return p;
>   }
>
> e.g.
>
>   int x = 6;
>   inc(inc(&x));
>   assert(x == 8);
>
> (This is a trivial example but is representative of a class of functions
> in the C++ API I am trying to bind.)
>
> In my bindings, C ints are represented in Lua as numbers. So, the above C
> example would be as follows in lua:
>
>   x = 6
>   inc(inc(x))
>   -- x now equals 8
>
> Any thoughts? If there is no way to pass or return values by reference, do
> I just outlaw pointers (and C++ references) in the C++ API?
>
>
> BTW the binding is automated by way of a SWIG Lua 5.0 language module; if
> anyone else is working on one, I would be happy to stop developing it and
> be a guinea pig for someone else's.
>
> A real function I'm trying to bind (if the above does not please you) is
>
>         const Vector3 & Vector3::Normalize()
>         {
>                 float mag = Magnitude();
>
>                 if(mag == 0.0f)
>                         return *this;
>
>                 float oo_mag = 1.0f/mag;
>                 mx *= oo_mag;
>                 my *= oo_mag;
>                 mz *= oo_mag;
>
>                 return *this;
>         }
>
>
>