Override

오버라이드의 소개

 오버라이드의 형식

Python

Override/1.py

class C1:
    def m(self):
        return 'parent'
class C2(C1):
    def m(self):
        return super().m() + ' child'
    pass
o = C2()
print(o.m())

Ruby

Override/1.rb

class C1
  def m()
    return 'parent'
  end
end
class C2 < C1
  def m()
    return super()+' child'
  end
end
o = C2.new()
p o.m()

실행결과

parent child

Python | Ruby

오버라이드의 활용 (Python)

Override/2.py 

class Cal(object):
    _history = []
    def __init__(self, v1, v2):
        if isinstance(v1, int):
            self.v1 = v1
        if isinstance(v2, int):
            self.v2 = v2
    def add(self):
        result = self.v1+self.v2
        Cal._history.append("add : %d+%d=%d" % (self.v1, self.v2, result))
        return result
    def subtract(self):
        result = self.v1-self.v2
        Cal._history.append("subtract : %d-%d=%d" % (self.v1, self.v2, result))
        return result
    def setV1(self, v):
        if isinstance(v, int):
            self.v1 = v
    def getV1(self):
        return self.v1
    @classmethod
    def history(cls):
        for item in Cal._history:
            print(item)
    def info(self):
        return "Cal => v1 : %d, v2 : %d" % (self.v1, self.v2)
class CalMultiply(Cal):
    def multiply(self):
        result = self.v1*self.v2
        Cal._history.append("multiply : %d*%d=%d" % (self.v1, self.v2, result))
        return result
    def info(self):
        return "CalMultiply => %s" % super().info()
class CalDivide(CalMultiply):
    def divide(self):
        result = self.v1/self.v2
        Cal._history.append("divide : %d/%d=%d" % (self.v1, self.v2, result))
        return result
    def info(self):
        return "CalDivide => %s" % super().info()

c0 = Cal(30, 60)
print(c0.info())
c1 = CalMultiply(10,10)
print(c1.info())
c2 = CalDivide(20,10)
print(c2.info())

Cal => v1 : 30, v2 : 60
CalMultiply => Cal => v1 : 10, v2 : 10
CalDivide => CalMultiply => Cal => v1 : 20, v2 : 10

ideone.com

오버라이드의 활용 (Ruby)

Override/2.rb 

class Cal
  attr_reader :v1, :v2
  attr_writer :v1
  @@_history = []
  def initialize(v1,v2)
    @v1 = v1
    @v2 = v2
  end
  def add()
    result = @v1+@v2
    @@_history.push("add : #{@v1}+#{@v2}=#{result}")
    return result
  end
  def subtract()
    result = @v1-@v2
    @@_history.push("subtract : #{@v1}-#{@v2}=#{result}")
    return result
  end
  def setV1(v)
    if v.is_a?(Integer)
      @v1 = v
    end
  end
  def getV1()
    return @v1
  end
  def Cal.history()
    for item in @@_history
      p item
    end
  end
  def info()
    return "Cal => v1 : #{@v1}, v2 : #{@v2}"
  end
end
class CalMultiply < Cal
  def multiply()
    result = @v1*@v2
    @@_history.push("multipy : #{@v1}*#{@v2}=#{result}")
    return result
  end
  def info()
    return "CalMultiply => #{super()}"
  end
end
class CalDivide < CalMultiply
  def divide()
    result = @v1/@v2
    @@_history.push("divide : #{@v1}/#{@v2}=#{result}")
    return result
  end
  def info()
    return "CalDivide => #{super()}"
  end
end
c0 = Cal.new(30, 60)
p c0.info()
c1 = CalMultiply.new(10, 10)
p c1.info()
c2 = CalDivide.new(20, 10)
p c2.info()

ideone.com

 참고

github