Python - オブジェクトとクラス(継承、メソッドのオーバーライド、追加、プロパティによる属性地の取得、非公開属性のための名前のマングリング、コンポジション)

入門 Python 3
原著

開発環境

• OS X El Capitan - Apple (OS)
• Emacs (Text Editor)
• Python 3.5 (プログラミング言語)

入門 Python 3 (Bill Lubanovic (著)、 斎藤 康毅(監修)、 長尾 高弘 (翻訳)、オライリージャパン)の6章(オブジェクトとクラス)、6.15(復習問題)を取り組んでみる。

コード(Emacs)

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

print('6.1')


class Thing:
    pass

print(Thing)

example = Thing()
print(example)

print('6.2')


class Thing2:
    letters = 'abc'

print(Thing2.letters)

print('6.3')


class Thing3:

    def __init__(self):
        self.letters = 'xyz'

print(Thing3().letters)

print('6.4')


class Element:

    def __init__(self, name, symbol, number):
        self.name = name
        self.symbol = symbol
        self.number = number

elem = Element('Hydrogen', 'H', 1)
print(elem.name, elem.symbol, elem.number)

print('6.5')

d = dict(name='Hydrogen', symbol='H', number=1)
elem = Element(**d)
print(elem.name, elem.symbol, elem.number)

print('6.6')


class Element1(Element):

    def dump(self):
        print(self.name, self.symbol, self.number)

hydrogen = Element1('Hydrogen', 'H', 1)
hydrogen.dump()

print('6.7')

print(hydrogen)


class Element2(Element):

    def __str__(self):
        return 'name: {0}, symbol: {1}, number: {2}'.format(
            self.name, self.symbol, self.number)

hydrogen = Element2('Hydrogen', 'H', 1)
print(hydrogen)

print('6.8')


class Element:

    def __init__(self, name, symbol, number):
        self.__name = name
        self.__symbol = symbol
        self.__number = number

    @property
    def name(self):
        return self.__name

    @property
    def symbol(self):
        return self.__symbol

    @property
    def number(self):
        return self.__number


hydrogen = Element2('Hydrogen', 'H', 1)
print(hydrogen.name, hydrogen.symbol, hydrogen.number)

print('6.9')


class Bear:

    def eats():
        return 'berries'


class Rabbit:

    def eats():
        return 'clover'


class Octothorpe:

    def eats():
        return 'campers'

for cls in [Bear, Rabbit, Octothorpe]:
    print(cls.eats())


print('6.10')


class Laser:

    def does(self):
        return 'disintegrate'


class Claw:

    def does(self):
        return 'crush'


class SmartPhone:

    def does(self):
        return 'ring'


class Robot:

    def __init__(self):
        self.laser = Laser()
        self.claw = Claw()
        self.smartPhone = SmartPhone()

    def does(self):
        for obj in [self.laser, self.claw, self.smartPhone]:
            print(obj.does())

robot = Robot()
robot.does()

入出力結果(Terminal, IPython)

$ ./sample.py 
6.1
<class '__main__.Thing'>
<__main__.Thing object at 0x10fdbb080>
6.2
abc
6.3
xyz
6.4
Hydrogen H 1
6.5
Hydrogen H 1
6.6
Hydrogen H 1
6.7
<__main__.Element1 object at 0x10fdbb128>
name: Hydrogen, symbol: H, number: 1
6.8
Hydrogen H 1
6.9
berries
clover
campers
6.10
disintegrate
crush
ring
$