python学习（9）- 面向对象3

爱被打了一巴掌 2022-12-24 02:54 117阅读 0赞

Python学习（8）- 面向对象2

[https://blog.csdn.net/caoyan0829/article/details/109810524][https_blog.csdn.net_caoyan0829_article_details_109810524]

面向对象的三大特性：

"""
    封装
    1.把属性封装到对象当中，方便调用
    2.把相同的功能封装同一方法中，方便调用
    """
    
    """
    继承
    1.顶级父类是Object
    2.如果不同类中有相同的行为或属性 可以用继承
    """
    
    
    """
    多态
    1.同一种事务，具有多种形态
    2.前提要有继承关系
    """
    
    
    class Animal(object):  # 父类 基类
        def __init__(self):
            self.name = "小黑"
    
            # 私有属性和行为不能继承
            self.__color = "三花"
    
        def eat(self):
            print('吃饭')
    
    
    class Sea(object):
        def dh(self):
            print("海洋动物")
    
    
    class Dog(Animal):  # 子类 派生类
        # 重写
        def eat(self):
            print('吃狗粮')
            # 调用父类方法 super
            super().eat()
    
    
    class Cat(Animal):  # 子类
        pass
    
    
    class Pig(Animal):
        pass
    
    
    class HaShiQi(Dog):  # 也有eat 方法等
        pass
    
    
    d = Dog()
    d.eat()
    # print(d.__color)
    print(d.name)
    c = Cat()
    c.eat()
    
    # 多继承   广度继承  继承顺序同级的优先
    class HaiShi(Animal,Sea):
        pass
    
    haishi = HaiShi()
    haishi.eat()
    haishi.dh()
    
    
    
    #isinstance(对象，类)  返回布尔
    
    
    #单例模式
    #不管创建了多少对象，我们在内存中只有一个唯一的对象
    
    class DanLi(object) :
        __instance = None #装对象的引用
    
        def __new__(cls, *args, **kwargs): #创建对象
            if cls.__instance is None:
                cls.__instance = super().__new__(cls)
                return  cls.__instance
            else:
                return cls.__instance
        def __init__(self,name): #给对象初始化，所以每次执行会初始化一个对象
            self.name = name
    
    
    d = DanLi('hashiq')
    d1 = DanLi('hashiq1')
    d2 = DanLi('hashiq2')
    
    print(id(d)) #2953367550416
    print(id(d1)) #2953367550944
    print(id(d2)) #2953367550320

Python学习（10）- 文件操作

[https://blog.csdn.net/caoyan0829/article/details/110530723][https_blog.csdn.net_caoyan0829_article_details_110530723]

[https_blog.csdn.net_caoyan0829_article_details_109810524]: https://blog.csdn.net/caoyan0829/article/details/109810524
[https_blog.csdn.net_caoyan0829_article_details_110530723]: https://blog.csdn.net/caoyan0829/article/details/110530723