Python - Classes and OOP(Designing with Classes)

Learning Python
(Oreilly & Associates Inc)
Mark Lutz (著)
(邦訳版)

開発環境

• OS X Mavericks - Apple(OS)
• Emacs (CUI)、BBEdit - Bare Bones Software, Inc. (GUI) (Text Editor)
• Python (プログラミング言語)

Learning Python (Mark Lutz (著)、Oreilly & Associates Inc)のPART Ⅵ.(Classes and OOP)、CHAPTER 31(Designing with Classes)、Test Your Knowledge: Quiz.1.~5.を解いてみる。

その他参考書籍

• Pythonチュートリアル 第2版
• Python クックブック 第2版 (原書(最新版))

Test Your Knowledge: Quiz.1.~5.

1. コード(BBEdit)

   sample.py

   #!/usr/bin/env python3
   #-*- coding: utf-8 -*-
   
   class Sup1:
       def meth1(self):
           print('Hello, Sup1!')
   
   class Sup2:
       def meth2(self):
           print('Hello, Sup2!')
   
   # 複数のクラスを継承
   class Sub(Sup1, Sup2): pass
   
   o = Sub()
   o.meth1()
   o.meth2()
   
   

   入出力結果(Terminal)

   $./sample.py
   Hello, Sup1!
   Hello, Sup2!
   $
   

2. コード(BBEdit)

   sample.py

   #!/usr/bin/env python3
   #-*- coding: utf-8 -*-
   
   class Sup:
       def meth1(self):
           print('delegation')
           self.meth2()
   
   class Sub1(Sup):
       def meth2(self):
           print('Hello, Sub1 World!')
   
   class Sub2(Sup):
       def meth2(self):
           print('Hello, Sub2 World!')
   
   if __name__ == '__main__':
       for i in (Sub1(), Sub2()):
           i.meth1()
   

   入出力結果(Terminal)

   $ ./sample.py
   delegation
   Hello, Sub1 World!
   delegation
   Hello, Sub2 World!
   $
   

3. コード(BBEdit)

   sample.py

   #!/usr/bin/env python3
   #-*- coding: utf-8 -*-
   
   class A:
       def meth(self, data):
           print('A: {0}'.format(data))
   
   class B:
       def meth(self, data):
           # composition
           a = A()
           a.meth(data)
           
   if __name__ == '__main__':
       b = B()
       b.meth('meth')
   

   入出力結果(Terminal)

   $ ./sample.py
   A: meth
   $
   

4. コード(BBEdit)

   sample.py

   #!/usr/bin/env python3
   #-*- coding: utf-8 -*-
   
   class A:
       # unbound method
       def meth1():
           print('Hello, unbound method!')
       # bound method
       def meth2(self):
           print('Hello, bound method!')
           
   if __name__ == '__main__':
       A.meth1()                   # unbound methodの呼び出し
       a = A()
       A.meth1()                   # unbound methodの呼び出し
       a.meth2()                   # bound methodの呼び出し
       A.meth2(a)                  # bound methodの呼び出し
   
       try:
           a.meth1()
       except Exception as err:
           print(type(err), err, err.args)
   
       try:
           A.meth2()
       except Exception as err:
           print(type(err), err, err.args)
   
       try:
           a.meth2()
       except Exception as err:
           print(type(err), err, err.args)
           
       try:
           a.meth2(a)
       except Exception as err:
           print(type(err), err, err.args)
   
       try:
           a.meth2(A)
       except Exception as err:
           print(type(err), err, err.args)
   

   入出力結果(Terminal)

   $ ./sample.py
   Hello, unbound method!
   Hello, unbound method!
   Hello, bound method!
   Hello, bound method!
   <class 'TypeError'> meth1() takes 0 positional arguments but 1 was given ('meth1() takes 0 positional arguments but 1 was given',)
   <class 'TypeError'> meth2() missing 1 required positional argument: 'self' ("meth2() missing 1 required positional argument: 'self'",)
   Hello, bound method!
   <class 'TypeError'> meth2() takes 1 positional argument but 2 were given ('meth2() takes 1 positional argument but 2 were given',)
   <class 'TypeError'> meth2() takes 1 positional argument but 2 were given ('meth2() takes 1 positional argument but 2 were given',)
   $
   

5. コード(BBEdit)

   sample.py

   #!/usr/bin/env python3
   #-*- coding: utf-8 -*-
   
   # pseudoprivate attributesは名前の衝突を避けるために使われる
   class A:
       def seta(self):
           self.__data = '__a'     # _A__data
           self.data = 'a'
       def p(self):
           print(self.__data, self.data)
   
   class B:
       def setb(self):
           self.__data = '__b'     # # _B__data
           self.data = 'b'
   
   class C(A, B): pass
   
   if __name__ == '__main__':
       o = C()
       o.seta()
       o.p()
   
       o.setb()
       o.p()
   
       print(o._A__data, o._B__data)
   

   入出力結果(Terminal)

   $ ./sample.py
   __a a
   __a b
   __a __b
   $