c++lualuabind

Instantiate lua classes using Luabind

Is it possible to instantiate Lua "classes" using Luabind from a c++ application? To illustrate the problem, consider the following simple Lua script:

class "Person"

function Person:__init(name)
    self.name = name
end

function Person:display()
    print(self.name)
end

I can instantiate this class in the same Lua script and everything works fine. However, I want to instantiate a new object from this class using Luabind from within my c++ application. I have tried the following:

luabind::object myObject = luabind::globals(L)["Person"]("John Doe");
myObject["display"]();

I would expect to see "John Doe" output to the console. Instead, I am greeted with a Lua runtime error. The call to create the new object seemingly works. The problem appears to be that self, in the display function, is nil.

Solution

  • self is nil because if you use the ":"-operator in lua, then lua will automatically provide the caller as first argument. so:

    somePerson:display() == somePerson.display(somePerson)

    Therefore you need to provide that self-argument too:

    luabind::object myObject = luabind::globals(L)["Person"]("John Doe");
myObject["display"](myObject);

    Or even better: Use the simple functions in luabind available for that purpose

    luabind::object myObject = luabind::globals(L)["Person"]("John Doe");
luabind::call_member<void>(myObject, "display");