Python - Classes and OOP(Advanced Class Topics)

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 32(Advanced Class Topics)、Test Your Knowledge: Quiz.1.~ 7.を解いてみる。

その他参考書籍

Test Your Knowledge: Quiz.1.~ 7.

コード(BBEdit)

sample.py

#!/usr/bin/env python3
#-*- coding: utf-8 -*-

# extend list class
# embedding
class MyList1:
    def __init__(self, data=[]):
        self.data = data
    # + 演算子のoverload、その他は省略 
    def __add__(self, other):
        print('__add__', end=' :')
        if isinstance(other, MyList1):
            other = other.data
        return MyList1(self.data + other)
    def __radd__(self, other):
        print('__radd__', end=':')
        return MyList1(other + self.data)
    def __str__(self):
        return "MyList1({0})".format(self.data)

# subclassing
class MyList2(list): pass

if __name__ == '__main__':
    o0 = MyList1()
    o1 = MyList1(['python'])
    o2 = MyList1([1, 2])
    myLists1 = [o0, o1, o2]
    l0 = []
    l1 = ['python']
    l2 = [1, 2]
    lists = [l0, l1, l2]
    objects1 = lists + myLists1
    for x in myLists1:
        print('MyList1 + MyList1')
        for y in myLists1:
            print('{0} + {1} = {2}'.format(x, y, x + y))
        print('MyList1 + list')
        for y in lists:
            print('{0} + {1} = {2}'.format(x, y, x + y))
        print('list + MyList1')
        for y in lists:
            print('{0} + {1} = {2}'.format(y, x, y + x))

    o3 = MyList2()
    o4 = MyList2(['python'])
    o5 = MyList2([1, 2])
    myLists2 = [o3, o4, o5]
    for x in myLists2:
        print('MyList2 + MyList2')
        for y in myLists2:
            print('{0} + {1} = {2}'.format(x, y, x + y))
        print('MyList2 + list')
        for y in lists:
            print('{0} + {1} = {2}'.format(x, y, x + y))
        print('list + MyList2')
        for y in lists:
            print('{0} + {1} = {2}'.format(y, x, y + x))

入出力結果(Terminal)

$ ./sample.py
MyList1 + MyList1
__add__ :MyList1([]) + MyList1([]) = MyList1([])
__add__ :MyList1([]) + MyList1(['python']) = MyList1(['python'])
__add__ :MyList1([]) + MyList1([1, 2]) = MyList1([1, 2])
MyList1 + list
__add__ :MyList1([]) + [] = MyList1([])
__add__ :MyList1([]) + ['python'] = MyList1(['python'])
__add__ :MyList1([]) + [1, 2] = MyList1([1, 2])
list + MyList1
__radd__:[] + MyList1([]) = MyList1([])
__radd__:['python'] + MyList1([]) = MyList1(['python'])
__radd__:[1, 2] + MyList1([]) = MyList1([1, 2])
MyList1 + MyList1
__add__ :MyList1(['python']) + MyList1([]) = MyList1(['python'])
__add__ :MyList1(['python']) + MyList1(['python']) = MyList1(['python', 'python'])
__add__ :MyList1(['python']) + MyList1([1, 2]) = MyList1(['python', 1, 2])
MyList1 + list
__add__ :MyList1(['python']) + [] = MyList1(['python'])
__add__ :MyList1(['python']) + ['python'] = MyList1(['python', 'python'])
__add__ :MyList1(['python']) + [1, 2] = MyList1(['python', 1, 2])
list + MyList1
__radd__:[] + MyList1(['python']) = MyList1(['python'])
__radd__:['python'] + MyList1(['python']) = MyList1(['python', 'python'])
__radd__:[1, 2] + MyList1(['python']) = MyList1([1, 2, 'python'])
MyList1 + MyList1
__add__ :MyList1([1, 2]) + MyList1([]) = MyList1([1, 2])
__add__ :MyList1([1, 2]) + MyList1(['python']) = MyList1([1, 2, 'python'])
__add__ :MyList1([1, 2]) + MyList1([1, 2]) = MyList1([1, 2, 1, 2])
MyList1 + list
__add__ :MyList1([1, 2]) + [] = MyList1([1, 2])
__add__ :MyList1([1, 2]) + ['python'] = MyList1([1, 2, 'python'])
__add__ :MyList1([1, 2]) + [1, 2] = MyList1([1, 2, 1, 2])
list + MyList1
__radd__:[] + MyList1([1, 2]) = MyList1([1, 2])
__radd__:['python'] + MyList1([1, 2]) = MyList1(['python', 1, 2])
__radd__:[1, 2] + MyList1([1, 2]) = MyList1([1, 2, 1, 2])
MyList2 + MyList2
[] + [] = []
[] + ['python'] = ['python']
[] + [1, 2] = [1, 2]
MyList2 + list
[] + [] = []
[] + ['python'] = ['python']
[] + [1, 2] = [1, 2]
list + MyList2
[] + [] = []
['python'] + [] = ['python']
[1, 2] + [] = [1, 2]
MyList2 + MyList2
['python'] + [] = ['python']
['python'] + ['python'] = ['python', 'python']
['python'] + [1, 2] = ['python', 1, 2]
MyList2 + list
['python'] + [] = ['python']
['python'] + ['python'] = ['python', 'python']
['python'] + [1, 2] = ['python', 1, 2]
list + MyList2
[] + ['python'] = ['python']
['python'] + ['python'] = ['python', 'python']
[1, 2] + ['python'] = [1, 2, 'python']
MyList2 + MyList2
[1, 2] + [] = [1, 2]
[1, 2] + ['python'] = [1, 2, 'python']
[1, 2] + [1, 2] = [1, 2, 1, 2]
MyList2 + list
[1, 2] + [] = [1, 2]
[1, 2] + ['python'] = [1, 2, 'python']
[1, 2] + [1, 2] = [1, 2, 1, 2]
list + MyList2
[] + [1, 2] = [1, 2]
['python'] + [1, 2] = ['python', 1, 2]
[1, 2] + [1, 2] = [1, 2, 1, 2]
$

staticmethodの定義するとき等にdecoratorを使う。
python3.xでは最初からすべてnew-style class(すべてのクラスがobjectを継承している)
3.の通り、new-style classはobjectから派生している。

normal methodはインスタンスと、static methodはクラスと結びついている。

コード(BBEdit)

sample.py

#!/usr/bin/env python3
#-*- coding: utf-8 -*-

class A:
    count = 0
    # static method
    def counter():
        print(A.count)
    # normal method
    def __init__(self):
        A.count += 1
    def meth(self):
        print('Hello, world!')
    

if __name__ == '__main__':
    a = A()
    A.counter()
    try:
        a.counter()
    except Exception as err:
        print(type(err), err, err.args)
    try:
        A.meth()
    except Exception as err:
        print(type(err), err, err.args)
    A.meth(a)
    a.meth()
    b = A()
    A.counter()

入出力結果(Terminal)

$ ./sample.py
1
<class 'TypeError'> counter() takes 0 positional arguments but 1 was given ('counter() takes 0 positional arguments but 1 was given',)
<class 'TypeError'> meth() missing 1 required positional argument: 'self' ("meth() missing 1 required positional argument: 'self'",)
Hello, world!
Hello, world!
2
$

yes.
pass

Kamimura's blog

2014年5月2日金曜日

Python - Classes and OOP(Advanced Class Topics)

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