内置类属性

内置类属性:python中每个类都拥有内置的类属性

• _name_
• _doc_
• _dict_
• _module_
• _bases_

代码实例

class Cat:
    猫类
    number = 0

    def __init__(self, name='', color='white'):
        self.name = name
        self.color = color

    def run(self):
        print(self.name, 'is running')

    @staticmethod
    def miao():
        print('miao')

    @classmethod
    def getNumber(cls):
        print('number:', cls.number)

1.name

获取类的名字(str)

print(Cat.__name__)
print(Cat.__name__)
cat1 = Cat('小白')

2.类.doc

获取类的说明文档

print(Cat.__doc__)

3.类.dict

对象.dict
获取所有属性和对应的值转换成字典

print(cat1.__dict__)
print(Cat.__dict__)

4.类.module
获取当前类所在的模块的名字

print(Cat.__module__)

5.类.bases
获取当前类的父类(元组,因为可以多继承)

print(Cat.__bases__)

私有化

• python中类中的属性和方法的私有化:直接在属性名或者方法名前加上(命名以''开头)
• 属性或者方法私有:在外部不能直接使用,可以在类的内部使用

import random


class Person:
    '''人类'''
    __number = 1  # 私有类字段

    def __init__(self, name='', age=0):
        self.name = name
        self.__age = age

    def showAge(self):
        print(self.__age - 10)
        self.__run()

    @classmethod
    def __showNum(cls):
        print(cls.__number)

    @staticmethod
    def __aaao(cls):
        print('static')
        cls.__showNum()

    def showAll(self, cls):
        Person.__aaao(Person)

    # 私有的对象方法,只能在内部调用
    def __run(self):
        print('%s is running' % self.name)


class Student:
    def __init__(self, name):
        self.name = name
        self.study_id = ''

    def __creat_id(self):
        return 'py1805' + str(random.randint(1, 50)).rjust(3, '0')

    def creat(self, name):
        stu = Student(name)
        stu.study_id = self.__creat_id()
        return stu


if __name__ == '__main__':
    p1 = Person('z3', 30)
    # print(p1.__age)
    # print(p1.__run())
    p1.showAge()
    p1.showAll(Person)
    # 私有化原理:在方法和属性前加上_类名
    print(Person._Person__number)

getter和setter

• 属性假私有化:声明对象属性的时候,在属性名前面加一个'_',来告诉别人这个属性不可以使用.要通过getter和setter来获取属性值和修改属性值

1.getter:获取属性值

@property
def 属性名(去掉下划线)(self):
    return 返回值

• 如果获取对象的某个属性前需要处理数据,就添加getter

2.setter:给属性赋值

• 一个属性必须要有getter,才能添加setter

@getter名.setter
def getter名(self,参数):
    self._getter名 = 参数

• 如果给对象赋值前需要处理数据,添加setter

class Student:
    '''学生类'''

    def __init__(self):
        # 声明属性前面加一个'_'是为了告诉别人这个属性不能直接使用
        self._name = ''
        self._score = 0
        self._age = 0

    # 给属性_name添加getter
    @property
    def name(self):
        return self._name

    # 给属性_name添加setter
    @name.setter
    def name(self, name):
        self._name = name

    @property
    def score(self):
        return self._score

    @score.setter
    def score(self, score):
        self._score = score

    @property
    def age(self):
        return str(self._age) + '岁'

    @age.setter
    def age(self, age):
        if 0 <= age <= 120:
            self._age = age
            return
        print('非法输入')


if __name__ == '__main__':
    stu1 = Student()
    stu1.score = 20

    stu1.age = 999
    print(stu1.age)
    print(stu1.score)

练习

import json


class Data(object):
    def __init__(self,
                 type='',
                 text='',
                 user_id='',
                 name='',
                 screen_name='',
                 width=0,
                 height=0,
                 themes=''):
        self.type = type
        self.text = text
        self.user_id = user_id
        self.name = name
        self.screen_name = screen_name
        self._width = width
        self._height = height
        self._themes = themes

    @property
    def width(self):
        return self._width

    @width.setter
    def width(self, width):
        self._width = int(width)

    @property
    def height(self):
        return self._height

    @height.setter
    def height(self, height):
        self._height = int(height)

    @property
    def themes(self):
        if not self._themes:
            return '无'

    @themes.setter
    def themes(self, themes):
        self._themes = themes


def main():
    filePath = './day13-面向对象(进阶)/data.json'
    datas = []
    with open(filePath, encoding='utf-8') as f:
        data = json.load(f)
    for i in data['data']:
        j = Data()
        j.type = i['type']
        j.text = i['text']
        j.user_id = i['user_id']
        j.name = i['name']
        j.screen_name = i['screen_name']
        j.width = i['width']
        j.height = i['height']
        j.themes = i['themes']
        datas.append(j)
    for i in datas:
        print(i.__dict__)
        print('-0-0-0-0-0-0-0-0-0-0-0-0')
    with open('./day13-面向对象(进阶)/datas.json', 'w') as f1:
        datas[0] = datas[0].__dict__
        datas[1] = datas[1].__dict__
        json.dump(datas, f1)


if __name__ == '__main__':
    main()

类的继承

• 子类:继承者
• 父类(超类):被继承者

1. 集成基础

• python中类是可以继承的,并且支持多继承

class 类名(父类列表):
    """类的说明"""
    属性
    方法

说明:所有类默认继承基类object

2.能继承哪些内容

继承:直接拥有父类的属性和方法(继承后父类的属性和方法还是存在)

• a.对象的属性和方法,类的字段和类方法,静态方法都可以继承(私有的继承无意义)
• b.slots的约束不会被继承

class Person:
    '''人类'''
    number = 666

    def __init__(self):
        self.name = ''
        self.age = 0
        self.gender = '男'

    def eat(self):
        print('%s在吃饭' % self.name)

    @classmethod
    def getNum(cls):
        return cls.number

    @staticmethod
    def destory():
        return print('aaaaa')


class Student(Person):
    '''学生类'''


if __name__ == '__main__':
    stu = Student()
    stu.name = '猪小明'
    print(stu.name, stu.age, stu.eat(), Student.number, Student.destory())