operators and overloaded functions support? about lua-intf

[SteveKChiu]

For Lua operators, you can just bind the function to special meta name, for example:

LuaBinding(L).beginClass<MyClass>("MyClass")
    ...
    .addFunction("__add", &MyClass::add)
    ...
.endClass();

For a complete list of Lua operator meta methods you can see Lua reference, under Metatables and Metamethods section.

Lua function overloads on the other hand will never work too well. For one thing, the Lua type conversion for number and string will make automatically bind to overloaded functions nearly impossible, and there is no way to enumerate C++ overloaded functions. Combine with other difficulty, I don't think there is a way to do that in compile time.

So if you plan to add a Lua overloads function (a function that do different things based on argument types), the best way is to use CFunction convention, and dispatch by yourself.

If you are talking about adding overloaded C++ function to Lua (pick one the overloaded function), you just need to static_cast to the proper function type before adding it. For example:

static int test(string, int);
static string test(string);

LuaBinding(L).beginModule("utils")

    // this will bind int test(string, int)
    .addFunction("test_1", static_cast<int(*)(string, int)>(&test))

    // this will bind string test(string), by using our LUA_FN macro
    // LUA_FN(return_type, func_name, func_arg_types...)
    .addFunction("test_2", LUA_FN(string, test, string))

    .endModule();

[krisr]

Thanks for the quick response Steve. This was very helpful. I recognize it's a bit tricky to support overloading automatically so I appreciate that it probably doesn't make sense. I'm glad to hear that I can access the metaclass when adding operators - other libraries I was using were not working with the metaclass directly.

I'm currently writing an automatic binding generator for your project using libclang. If you are interested, I'd be happy to share the source when I'm further along.

[SteveKChiu]

Thanks for contribution. Yeah, I think it is interesting topic, and want to take a look at it.