我的Python第五篇 面向对象

一、类（class）的定义
1.定义一个类

>>> class Cocacola:    formula = ['caffeine','sugar','water','soda']    def drink(self):        print('Energy!')>>> >>> coke_for_me = Cocacola()>>> coke_for_you = Cocacola()>>> coke_for_me.formula['caffeine', 'sugar', 'water', 'soda']>>> coke_for_me.drink()Energy!>>> 

2.类的属性
在类当中赋值的变量，就是类的变量，就是类的属性。

>>> class Cocacola:    formula = ['caffeine','sugar','water','soda']>>> coke_for_me = Cocacola()>>> coke_for_me.formula['caffeine', 'sugar', 'water', 'soda']

3.类的实例化
将类的定义赋予一个实例

>>> class Cocacola:    formula = ['caffeine','sugar','water','soda']>>> coke_for_me = Cocacola()>>> coke_for_me.formula['caffeine', 'sugar', 'water', 'soda']

4.类属性的引用
类的实例可以引用类的属性，类的属性会被类的实例共享。类的属性可以遍历。

>>> >>> Cocacola.formula['caffeine', 'sugar', 'water', 'soda']>>> coke_for_me.formula['caffeine', 'sugar', 'water', 'soda']>>> coke_for_you.formula['caffeine', 'sugar', 'water', 'soda']>>> 

>>> >>> for i in Cocacola.formula:    print(i)caffeinesugarwatersoda>>> for i in coke_for_me.formula:    print(i)caffeinesugarwatersoda>>> 

5.实例属性
实例可以赋值新的变量，实例的变量就是实例的属性。

>>> >>> class Cocacola:    formula = ['caffeine', 'sugar', 'water', 'soda']>>> coke_for_me = Cocacola()>>> coke_for_me.new_taste = 'cherry'>>> print(coke_for_me.new_taste)cherry>>> 

6.实例方法
A.

>>> >>> class Person:    def sport(self):        print('Run!')        print('Jump!')>>> xiaoming = Person()>>> xiaoming.sport() # 这里不需要输入参数Run!Jump!>>> 

B.更多的参数：

>>> >>> class Beer:    formula = ['Hops','Malt_dust','yeast','wather']    def drink(self,how_much):        if how_much == 'a sip':            print('Cool~~')        elif how_much == 'whole bottle':            print('Headache!')>>> Tsingtao_Beer = Beer()>>> Tsingtao_Beer.drink('a sip')Cool~~>>> Tsingtao_Beer.drink('whole bottle')Headache!>>> 

8.self
被创建的实例本身，将一个对象作为一个参数放入函数中。如果类的方法中只有一个self，则类的实例引用方法时不需要再额外填入一个参数。
9.__init__() 魔术方法
初始化，可以在类中直接创建实例的方法并加以引用。

>>> >>> class Beer:    formula = ['Hops','Malt_dust','yeast','wather']    def __init__(self):        for element in self.formula:            print('The beer has {}'.format(element))>>> Tsingtao_Beer = Beer('青岛啤酒')The beer has HopsThe beer has Malt_dustThe beer has yeastThe beer has wather>>> 

二、类的继承