Class Definition and Instantiation

require 'cls'

class 'Worker'  --define class Worker
{
    __init__ = function(self, id)  --initializer
        self.id = id  --initialize instance member
    end;

    showId = function(self)  --method
        print('My worker id is ' .. self.id .. '.')
    end
}

w = Worker(100)  --create an object of Worker
w:showId()       --call Worker's method

Output:

My worker id is 100.

Inheritance and Polymorphism

require 'cls'

--class 'Worker' ... defined as above

class 'Person'
{
    __init__ = function(self, name)
        self.name = name
    end;

    say = function(self)
        print('Hello, my name is ' .. self.name .. '.')
        self:saySthElse()
    end;

    saySthElse = function(self)  --will be override later
    end
}

class 'Employee: Person, Worker'  --Employee inherits Person and Worker
{
    __init__ = function(self, name, salary, id)
        Person.__init__(self, name)  --call base's initializer directly
        Worker.__init__(self, id)
        self.salary = salary
    end;

    saySthElse = function(self)
        print('My salary is ' .. self.salary .. '.')
    end
}

e = Employee('Bob', 1000, 1)
e:say()
e:showId()

Output:

Hello, my name is Bob.
My salary is 1000.
My worker id is 1.

Next

See https://github.com/coin8086/lua-class-lib/wiki/API-Reference for API details, and https://github.com/coin8086/lua-class-lib/wiki/Lua-and-OOP for a deeper view on OOP in Lua.