Original Address http://www.freecls.com/a/2712/1b

The most similar thing to objects and classes in lua is that tables have methods and properties, so classes and objects can only be simulated using tables
To state that tables are already capable of handling most scenarios, and that the lua scripting language is not an object-oriented language (its advantage is lightweight, simple and fast), so it is sometimes amazing to emulate object-oriented, so the following is for learning only and is not recommended for formal environments.

Example

--Declare a Base Class Web
local Web = {name='freecls', url='http://www.freecls.com', dt='2018', server='aliyun'}
function Web:say_name()
    print(self.name)
end

function Web:say_url()
    print(self.url)
end

function Web:new(name,url)
    local o = {}
    setmetatable(o,self)
    
    --take o Meta-table of__index Metamethod set to Web
    --that o Attributes that are not in the Web Find in Tables
    self.__index = self
    
    --If passed name,url Set to Table o in
    --If not, follow it Web Content inside
    if name ~= nil then o.name = name end
    if url ~= nil then o.url = url end
    
    return o
end


local w1 = Web:new('Cang Lang Shui')

--Cang Lang Shui	http://www.freecls.com	2018	aliyun
print(w1.name, w1.url, w1.dt, w1.server)

w1:say_name()       --Cang Lang Shui



local w2 = Web:new('Dai Lei', 'http://www.freecls.com/u/info/2712')

--Dai Lei	http://www.freecls.com/u/info/2712	2018	aliyun
print(w2.name, w2.url, w2.dt, w2.server)

w2:say_name()       --Dai Lei

Simulated Inheritance

--Declare a Base Class Web
--Notice this Web The table has changed a lot to be inherited
local Web = {name='freecls', url='http://www.freecls.com', dt='2018', server='aliyun'}
function Web:say_name()
    print(self.name)
end

function Web:say_url()
    print(self.url)
end

function Web:new(name,url)
    local o = {}
    setmetatable(o,self)
    
    --take o Meta-table of__index Metamethod set to Web
    --that o Attributes that are not in the Web Find in Tables
    self.__index = self
    
    if name ~= nil then o.name = name else o.name = self.name end
    if url ~= nil then o.url = url else o.url = self.url end
    o.dt = self.dt
    o.server = self.server
    
    o.say_name = self.say_name
    o.say_url = self.say_url
    
    return o
end


local Web1 = {age=22,sex='male'}

function Web1:how_old()
    print(self.age)
end

--Simulated Inheritance
function Web1:new(age,sex)
    local o = Web:new()
    setmetatable(o, self)
    self.__index = self
    
    return o
end

local w1 = Web1:new()
w1.name = 'Cang Lang Shui'

--22	male	Cang Lang Shui	http://www.freecls.com	2018	aliyun
print(w1.age, w1.sex, w1.name, w1.url, w1.dt, w1.server)

w1:say_url()        --http://www.freecls.com
w1:say_name()       --Cang Lang Shui
w1:how_old()        --22

Analog Rewrite

local Web = {name='freecls', url='http://www.freecls.com', dt='2018', server='aliyun'}
function Web:say_name()
    print(self.name)
end

function Web:say_url()
    print(self.url)
end

function Web:new(name,url)
    local o = {}
    setmetatable(o,self)
    
    --take o Meta-table of__index Metamethod set to Web
    --that o Attributes that are not in the Web Find in Tables
    self.__index = self
    
    if name ~= nil then o.name = name else o.name = self.name end
    if url ~= nil then o.url = url else o.url = self.url end
    o.dt = self.dt
    o.server = self.server
    
    o.say_name = self.say_name
    o.say_url = self.say_url
    
    return o
end


local Web1 = {age=22,sex='male'}

function Web1:how_old()
    print(self.age)
end

--This method will fail and the override will fail
function Web1:say_name()
    print(self.name..' Rewrite')
end

--Simulated Inheritance
function Web1:new(age,sex)
    local o = Web:new()
    setmetatable(o, self)
    self.__index = self
    
    --Rewrite succeeded
    function o:say_name()
        print(self.name..' Rewrite')
    end
    
    return o
end

local w1 = Web1:new()
w1.name = 'Cang Lang Shui'

--22	male	Cang Lang Shui	http://www.freecls.com	2018	aliyun
print(w1.age, w1.sex, w1.name, w1.url, w1.dt, w1.server)

w1:say_url()        --http://www.freecls.com
w1:say_name()       --Cang Lang Shui Rewrite
w1:how_old()        --22

summary

1. This article is only a brief introduction to lua simulation object-oriented, if you have questions, you can leave a message for me
2.lua version 5.1, running environment centos7 64 bit
3. Original Address http://www.freecls.com/a/2712/1b