Re: [ANN] luabind 0.9-rc1

Colm Sloan wrote:
> Fantastic work. I didn't realize how much had been done. Where can I read
> more about these two points?:

Both of these features are actually not documented due to lack of time.
Here's a short explanation though:

>  * Automatically perform down-casts as well as up-casts when converting
>   arguments from Lua to C++.

Rather than just cast up to base types, we search the graph in both
directions. See example below.

>  * When converting from C++ to Lua, polymorphic instances are
>   automatically cast to their most derived type.

This means that code like this:

  struct X
  {
      virtual ~X() {}
  };

  struct Y : X
  {
      void f();
  };

  X* make()
  {
      return new Y;
  }

  void take(Y*);

  ...

    class_<X>("X"),
    class_<Y, X>("Y")
      .def("f", &Y::f, adopt(result)),
    def("make", &make),
    def("take", &take)

.. and later in Lua:

  x = make()
  x:f()

will work. The dynamic type of the instance returned from make() will be
used to determine the class.

  take(x)

will also work, because luabind can cast the held X* down to a Y*.

HTH,
-- 
Daniel Wallin
BoostPro Computing
http://www.boostpro.com

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