lua的面向对象实例

local PI = 3.1415926
  
  s = {area = 0, r = 0}
  --派生类的方法
  s.new = function(self, o, r)
      o = o or {}
      setmetatable(o, self)
      self.__index = self
      self.r = r
      self.area = r*r*PI
      return o
  end
  
  s.printArea = function(self)
      print("area = ", self.area)
  end
  
  local model1 = s:new(nil, 4)
  model1:printArea()
  local model2 = s:new(nil, 5)
  model2:printArea()
  local model3 = s:new(nil, 6)

  model3:printArea()

请按 ENTER 或其它命令继续
area = 50.2654816
area = 78.539815
area = 113.0973336