Re: Calling C++ class methods from Lua (newbie)

[rob <lua@...>]

Henderson, Michael D wrote:

> Hi. I'm using the 5.1-alpha package. I am changing C++ programs to use 
> configuration files written in Lua. It is a joy to see a future where 
> I am not maintaining many different custom parsers :)
>
> This may not be the best approach, but I'm trying to make the lua 
> script call directly into the C++ class that maintains the application 
> environment. The parser was written in C++, so it carried around a 
> context pointer and would call the methods directly 
> (context->SetHostName(someString)). I've created a C/Lua function (in 
> this example int fLua_SetHostName(lua_State *L);) that knows how to 
> call the C++ class to set the host name.
>
> I'm able to retrieve the string, but I'm having difficulty 
> understanding how to deal with the class pointer. I'm wondering how to 
> pass in the context. I can create a global external to the function 
> (ApplicationEnvironment *context;) but some of our applications are 
> threaded and need multiple contexts.
>
> I would like to push a pointer to the context on to the Lua stack, but 
> I'm not at all sure how to push it on and pull it off. Do I create a 
> lua_State for each thread? Would I (should I) push the context onto 
> the stack, or would I be better off putting it in a table? I think 
> that tables would be more flexible. Either way, how can I handle C++ 
> pointers on the stack or in tables?
>
> Thanks
> Mike
You could look at luabind or tolua++, both allow you to deal directly 
with c++ classes.