​x
-- 基类
Person = {}

-- 基类中的方法
function Person:say()
    print(string.format("I am %s, %d years old.", self.name, self.age))
end

-- 子类
Student = {}
-- 为子类设置元表。不允许获取和设置子类的元表，防止继承结构被破坏
setmetatable(Student, { __index = Person, __metatable = "permission denied" })

-- 子类的构造方法
function Student:new(name, age, grade)
    return setmetatable({ name = name or "", age = age or 0, grade = grade or 1 }, {
        __index = self,
        -- 不允许获取和设置对象的元表，防止继承结构被破坏
        __metatable = "permission denied" })
end

function Student:study()
    print(string.format("I am studying %d grade courses", self.grade))
end

Teacher = {}
setmetatable(Teacher, { __index = Person, __metatable = "permission denied" })

function Teacher:new(name, age, grade)
    return setmetatable(
            { name = name or "", age = age or 0, grade = grade or 1 },
            { __index = self, __metatable = "permission denied" }
    )
end

function Teacher:teach()
    print(string.format("I am teaching %d grade courses", self.grade))
end

s = Student:new("Gloria", 8, 1)
s:say()
s:study()

t = Teacher:new("Tim", 30, 2)
t:say()
t:teach()

输出：

xxxxxxxxxx
I am Gloria, 8 years old.
I am studying 1 grade courses
I am Tim, 30 years old.
I am teaching 2 grade courses