Python类

在类的变量前面加 _ _ 是私有变量，外部不可访问。

需要注意的是，在Python中，变量名类似__xxx__的，也就是以双下划线开头，并且以双下划线结尾的，是特殊变量，特殊变量是可以直接访问的，不是private变量，所以，不能用__name__、__score__这样的变量名。

# coding=utf8

class Student(object):

    def __init__(self, name, score):
        self.__name = name
        self.__score = score

    def print_score(self):
        print('%s: %s' % (self.__name, self.__score))

bart = Student('Bart Simpson', 98)
print(bart.__name)

示例二：

# coding=utf8

class Student(object):

    def __init__(self, name, score):
        self.__name = name
        self.__score = score

    def print_score(self):
        print('%s: %s' % (self.__name, self.__score))

    # 让外部获取name和score
    def get_name(self):
        return self.__name

    def get_score(self):
        return self.__score

    # 设置分数
    def set_score(self, score):
        if 0 <= score <= 100:
            self.__score = score
        else:
            raise ValueError('bad score')

bart = Student('Bart Simpson', 98)
print(bart.get_name())
print(bart.get_score())
bart.set_score(80)
print(bart.get_score())
# print(bart.set_score('str'))

Python内置的@property装饰器就是负责把一个方法变成属性调用的

# coding=utf8

class Student(object):

    @property
    def birth(self):
        return self._bith

    @birth.setter
    def birth(self, value):
        self._birth = value

    @property
    def age(self):
        return 2015 - self._birth

s = Student()
s.birth = 1980
print(s.age)

多重继承

# coding=utf8

class Animal(object):
    pass

# 大类
class Mammal(Animal):
    pass

class Bird(Animal):
    pass

# 各种功能
class Runnable(object):
    def run(self):
        print('Running...')

class Flyable(object):
    def fly(self):
        print('Flying...')

# 各种动物
class Dog(Mammal, Runnable):
    pass

class Bat(Mammal, Flyable):
    pass

class Parrot(Bird, Flyable):
    pass

class Ostrich(Bird, Runnable):
    pass

定制类

# coding=utf8

class Student(object):
    def __init__(self, name):
        self.name = name
    def __str__(self):
        return 'Student object (name: %s)' % self.name

print(Student('Michael'))

另一个实例：
# coding=utf8

class Student(object):

    def __init__(self):
        self.name = 'Michael'

    def __getattr__(self, attr):
        if attr == 'score':
            return 99
        raise AttributeError('\'Student\' object has no attribute \'%s\'' % attr)

s = Student()
print(s.name)
print(s.score)

直接对实例进行调用

# coding=utf8

# 直接对实例进行调用
class Student(object):
    def __init__(self, name):
        self.name = name

    def __call__(self):
        print('My name is %s.' % self.name)

s = Student('Michael')
s()

枚举类

# coding=utf8

from enum import Enum

Month = Enum('Month', ('Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'))

for name, member in Month.__members__.items():
    print(name, '=>', member, ',', member.value)

结果：