实现加法(__add)重载代码示例：

复制代码 代码如下:
do
local Infor_class = {};

function Infor_class.create(_t)
local newTable = {};
setmetatable(newTable, Infor_class); --set the metatable
for i, v in pairs(_t) do
newTable[i] = v;
end
return newTable;
end

function Infor_class.sum(c1, c2)
if(#c1 ~= #c2) then
return nil;
else
local result = {};
local len = #c1;
for i = 1, len do
result[i] = c1[i] + c2[i];
end
print("result");
return result;
end
print("nil");
return nil;
end

Infor_class.__add = Infor_class.sum --override the _add

r1 = Infor_class.create{3, 4}
r2 = Infor_class.create{5, 6};

result = r1 + r2;
print(unpack(result));
end