簡單的方法

我們可以用一種簡單的方式來達到 OOP 的模擬，這個方法中，我們只會用到對表格的操作。以角色類別舉例：Character 只包含一個函式 new，透過在 new 中宣告的區域變數 character 建立一個新的實體，並在 new 之中將 character 的成員定義好，最後將它回傳。繼承的方式是在新類別的 new 方法直接使用被繼承類別的 new 方法，直接取得被繼承類別的新物件，並直接在該物件添加新法法與新屬性。這樣的方式在使用上相當直觀，而且很好理解，但缺點就是你必須將類別成員都在 new 中定義好，無法在外部定義。

----------------
-- Character.lua
----------------
-- Define the base object
local Character = {}
-- Create the constructor function
-- This lets you pass in table values to override the defaults and make your object unique
Character.new = function( options )
    local character = {}
    character.name = (options and options.name) or "Noname"
    character.job = (options and options.job) or "Homeless"
    character.power = (options and options.power) or 4
    character.weapon = (options and options.weapon) or "fist"
    -- Add a method to the object
    function character:attack()
      print(string.format("%s %s use %s with power %d to attack", self.job, self.name, self.weapon, self.power))
    end

    return character
end
return Character

----------------
-- Warrior.lua
----------------
local Character = require("Character")
-- Define the base object
local Warrior = {}

-- Create the constructor function
-- This lets you pass in table values to override the defaults and make your objectique
Warrior.new = function( options )
  options = options or {}
  options.job = "Warrior"
  options.weapon = "sword"
  options.power = options.power or 100

  local warrior =  Character.new(options)

  function warrior:shieldBash()
    print(string.format("%s %s use shield bash", self.job, self.name))
  end

  return warrior
end

return Warrior

----------------
--Mage.lua
----------------
local Character = require("Character")
-- Define the base object
local Mage = {}

-- Create the constructor function
-- This lets you pass in table values to override the defaults and make your objectique
Mage.new = function( options )
  options = options or {}
  options.job = "Mage"
  options.weapon = "stick"

  local mage = Character.new(options)
  -- Add a method to the object
  function mage:attack()
   print(string.format("%s %s use %s with power %d to attack", self.job, self.name, self.weapon, self.power))
  end

  function mage:fire()
   print(string.format("%s %s use fire art", self.job, self.name))
  end

  function mage:ice()
   print(string.format("%s %s use ice art", self.job, self.name))
  end

  return mage
end

return Mage

----------------
--Paladin.lua
----------------
local Warrior = require("Warrior")
-- Define the base object
local Paladin = {}

-- Create the constructor function
-- This lets you pass in table values to override the defaults and make your objectique
Paladin.new = function( options )
  options = options or {}
  options.job = "Paladin"
  options.power = options.power or 200

  local paladin =  Warrior.new(options)
  -- Add a method to the object
  function paladin:heal()
    print(string.format("%s %s use heal art", self.job, self.name))
  end

  return paladin
end

return Paladin

----------------
--main.lua
----------------
local Character = require("Character")
local Warrior = require("Warrior")
local Paladin = require("Paladin")
local Mage = require("Mage")

local Kevin = Character.new({name = "kevin"})
local Mary = Mage.new({name = "Mary", power = 5})
local Mark = Mage.new({name = "Mark"})
local Steve = Warrior.new({name = "Hank"})
local Edison = Paladin.new({name = "Edison"})

Kevin:attack()
Mary:attack()
Mary:ice()
Mark:attack()
Mark:fire()
Steve:attack()
Steve:shieldBash()
Edison:attack()
Edison:shieldBash()
Edison:heal()