LUA implements multiple inheritance

Lua supports object-oriented support primarily through table, where each table is an object, and for inheritance, LUA has a meta-table mechanism through which the setmetatble () can be used to modify the meta-table.

What is MetaTable?

MetaTable in fact is in itself can not find things, will go to the meta-table to find.

__index Meta-method:

The __index method is used to determine how a table looks when it is used as a meta-table. Its value allows the function to be a table, and the general usage is:

local obj = {}setmetatable(obj, {__index = xx})   --这样便实现了obj实现继承自xx。

For multiple inheritance, the principle is to traverse multiple parent classes, the code is as follows:

local class1 = {}function class1:new()    local obj = {}    setmetatable(obj, {__index= class1})    return objendfunction class1:print1()    print("class1:print()")endlocal class2 = {}function class2:new()    local obj = {}    setmetatable(obj, {__index= class2})    return objendfunction class2:print2()    print("class2:print()")endfunction super(k, list)    for i,v in ipairs(list) do        local ret = v[k]        if ret then            return ret        end    endendlocal class3 = {}function class3:new()    local obj = {}    local  base = {class1, class2}    --t为调用的对象,k为方法名    setmetatable(class3, {__index= function(t,k) return super(k, base) end})    setmetatable(obj, {__index = class3})    return objend

Result output:

Class1:print ()

Class2:print ()

LUA implements multiple inheritance