Re: ::className and ::member in luna.h

["Ry Lowry" <rylowry@...>]

Ah, I understand now!  I did not do a very good job of studying the
objects that were being passed to Luna.  I was assuming that
::className and ::methods were some dark magic I had not yet learned,
but they were just plain old static members of the class that was
being passed to Luna.  That's the danger of assuming!  Time to go get
a glass of water and just sit on it for a while.  Thanks again for the
light bulb moment.

On Tue, Jul 8, 2008 at 12:27 AM, James Dennett <james.dennett@gmail.com> wrote:
> On Mon, Jul 7, 2008 at 10:18 PM, Ry Lowry <rylowry@gmail.com> wrote:
>> Hello all,
>>
>> I am a new comer to Lua.  Currently I am working on a simple C++ app
>> that renders a cube to the screen using OpenGL, and exposes cube
>> functionality to Lua.  I have created a class to represent the cube,
>> and I have been experimenting with it in various ways.  Before I
>> worried about doing anything object oriented from Lua, I created a few
>> procedural functions to modify the cube.  During that phase I created
>> and destroyed the Cube manually in my C++ code.  However, I am now
>> moving on and attempting to learn how to expose my Cube class to Lua
>> so that it can be used in an OO style from a script.  To accomplish
>> this, I have been studying the Luna class provided at
>> http://lua-users.org/wiki/SimplerCppBinding.
>>
>> Using luna.h as a reference, I have managed to create a "new" method
>> for the Cube that Lua can call.  All of the Cubes that are getting
>> created in the Lua script are also being automatically deleted when
>> lua_close() is called (thanks to the "__gc" metamethod).  However,
>> both the "new" and "destroy" methods that I created were hand built
>> for the Cube class.  To complete my learning exercise, I would like to
>> create a set of template functions that essentially replicate what
>> luna.h already does.
>>
>> However, as I was going through the code, I came across the following
>> lines which threw me off:
>>
>> luaL_newmetatable(L, T::className);
>>
>> for (RegType *l = T::methods; l->name; l++) {
>>
>> I did not realize ::className and ::methods were available at all.
>
> There's nothing special about those names to C++.  They're just
> variables defined in the program, static members of the type T by some
> convention.  Luna could have used a different set of names just as
> well.
>
> -- James
>