Lua Meta API

function get(object)
    return getmetatable(object or {}) or {};
end;

function set(object, metatable)
    return setmetatable(object or {}, metatable or {});
end;

function mod(object, metatable, override)
    local omt = get(object);
    for mk, mv in pairs(omt) do
        if override then
            omt[mk] = mv; else
            omt[mk] = omt[mk] or mv; end;
    end; return set(object, omt);
end;

function clear(object)
    return set(object);
end;

function index(object, ...)
    local index = get(object).index or {};
    for ik, iv in ipairs({...}) do
        index[ik] = iv;
    end;

    local omt = {
        __index = function(object, key)
            local omt = get(object);
            for _, i in ipairs(omt.index or {}) do
                if i[key] then return i[key] end
            end;
        end;
    };

    omt.index = index;
    return mod(object, omt);
end;

function call(object, call)
    return mod(object, {
        __call = function(self, ...)
            return call(self, ...);
        end;
    });
end;