Student = {};
Student.__index = Student;

function Student:new(name, age)
    local temp = {};
    setmetatable(temp, Student);
    temp.name = name;
    temp.age = age;
    return temp;
end


function Student:info()
    print(self.name, self.age);
--运行stu2时会报错
--  print("name:" .. self.name .. " age:" .. self.age);
end

--输出:stu1    10
stu1 = Student.new(nil, "stu1", 10);    
stu1:info();

--输出:10    nil
stu2 = Student.new("stu2", 10);    
stu2:info();

--输出:nil    stu3
stu3 = Student:new(nil, "stu3", 10);    
stu3:info();

--输出:stu4    10
stu4 = Student:new("stu4", 10);    
stu4:info();

Student = {};
Student.__index = Student;

--此处做修改
function Student.new(name, age)
    local temp = {};
    setmetatable(temp, Student);
    temp.name = name;
    temp.age = age;
    return temp;
end


function Student:info()
    print(self.name, self.age);
end

--输出:nil    stu1
stu1 = Student.new(nil, "stu1", 10);    
stu1:info();

--输出:stu2    10
stu2 = Student.new("stu2", 10);    
stu2:info();

--输出:table: 0037B200    nil
stu3 = Student:new(nil, "stu3", 10);    
stu3:info();

--输出:table: 0037B200    stu4
stu4 = Student:new("stu4", 10);    
stu4:info();

--输出:table: 0084B200    stu5
stu5 = Student:new("stu5");    
stu5:info();

--输出:stu6    10
stu6 = Student:new("stu6", 10);    
stu6.info(stu6);

Student = {};
Student.__index = Student;

function Student.new(name, age)
    local temp = {};
    setmetatable(temp, Student);
    temp.name = name;
    temp.age = age;
    return temp;
end


function Student:info()
    print(self.name, self.age);
end

function Student:message()
    print(self.name, self.age);
end

function Student.school()
    print("go to school!!!");
end

--声明类时用点号:Student.new(name, age)
stu = Student:new("zhangsan", 10);
stu:info();    --输出信息错误
stu.school();
--stu.message(); --报错
stu.message(stu);--输出信息错误

mes = Student.new("zhangsan", 10);
--mes.info();    --报错
mes.info(mes);
mes.school();



--声明类时用冒号:Student.new(name, age)
--stu = Student:new("zhangsan", 10);
--stu:info();
--stu.info(stu);
--stu.school();

--mes = Student.new(nil, "mes", 20);
--mes:message();
--mes.school();