객체와 변수

인캡슐레이션(캡슐화)

 인스턴스 변수의 특성

Python

class C(object):
    def __init__(self, v):
        self.value = v
    def show(self):
        print(self.value)

c1 = C(10)
print(c1.value)
c1.value = 20
print(c1.value)
c1.show()

10
20
20

ideone.com 

Ruby

class C
  def initialize(v)
    @value = v
  end
  def show()
    p @value
  end
end
c1 = C.new(10)
# p c1.value
# c1.value = 20
c1.show()

10

ideone.com 

 set / get 메소드

Python

class C(object):
    def __init__(self, v):
        self.value = v
    def show(self):
        print(self.value)
    def getValue(self):
        return self.value
    def setValue(self, v):
        self.value = v
c1 = C(10)
print(c1.getValue())
c1.setValue(20)
print(c1.getValue())

10
20

ideone.com

class C
  def initialize(v)
    @value = v
  end
  def show()
    p @value
  end
  def getValue()
    return @value
  end
  def setValue(v)
    @value = v
  end
end
c1 = C.new(10)
# p c1.value
p c1.getValue()
# c1.value = 20
c1.setValue(20)
p c1.getValue()

10
20

ideone.com

set/get 메소드를 사용하는 이유

Python 

class Cal(object):
    def __init__(self, v1, v2):
        if isinstance(v1, int):
            self.v1 = v1
        if isinstance(v2, int):
            self.v2 = v2
    def add(self):
        return self.v1+self.v2
    def subtract(self):
        return self.v1-self.v2
    def setV1(self, v):
        if isinstance(v, int):
            self.v1 = v
    def getV1(self):
        return self.v1
c1 = Cal(10,10)
print(c1.add())
print(c1.subtract())
c1.setV1('one')
c1.v2 = 30
print(c1.add())
print(c1.subtract())

20
0
40
-20

ideone.com

 Ruby

class Cal
  attr_reader :v1, :v2
  attr_writer :v1
  def initialize(v1,v2)
    @v1 = v1
    @v2 = v2
  end
  def add()
    return @v1+@v2
  end
  def subtract()
    return @v1-@v2
  end
  def setV1(v)
    if v.is_a?(Integer)
      @v1 = v
    end
  end
  def getV1()
    return @v1
  end
end
c1 = Cal.new(10,10)
p c1.add()
p c1.subtract()
c1.setV1('one')
c1.v1 = 20
p c1.add()
c1.getV1()

20
0
30

ideone.com

속성

수업에서는 구분하지 않았습니다만 외부에서 접근 가능한 변수를 파이썬은 property 루비는 attribute라고 합니다. 

 Python

class C(object):
    def __init__(self, v):
        self.__value = v
    def show(self):
        print(self.__value)
c1 = C(10)
#print(c1.__value)
c1.show()

10

ideone.com

Ruby

class C
  #attr_reader :value
  #attr_writer :value
  attr_accessor :value
  def initialize(v)
    @value = v
  end
  def show()
    p @value
  end
end
c1 = C.new(10)
p c1.value
c1.value = 20
p c1.value

10
20

ideone.com

참고

github