主动调用其他类的成员, 特殊成员

class Base(object):
    def f1(self):
        print(‘5个功能‘)
obj = Base()
Base.f1(obj)
obj.f1()

class Base(object):

    def f1(self):
        print(‘5个功能‘)

class Foo(object):

    def f1(self):
        print(‘3个功能‘)
        Base.f1(self)

obj = Foo()
obj.f1()

class Base(object):
    def f1(self):
        print(‘5个功能‘)

class Foo(Base):
    def f1(self):
        super().f1()
        print(‘3个功能‘)
        
obj = Foo()
obj.f1()

class Foo(object):
    def f1(self):
        super().f1()
        print(‘3个功能‘)

class Bar(object):
    def f1(self):
        print(‘6个功能‘)

class Info(Foo,Bar):
    pass

# obj = Foo()
# obj.f1()      # Foo中没有继承Bar, super()会报错

obj = Info()
obj.f1()

class Foo(object):

    def __init__(self,a1,a2):
        self.a1 = a1
        self.a2 = a2
    
    def __call__(self, *args, **kwargs):
        print(11111,args,kwargs)
        return 123

    def __getitem__(self, item):
        print(item)
        return 8

    def __setitem__(self, key, value):
        print(key,value,111111111)

    def __delitem__(self, key):
        print(key)

    def __add__(self, other):
        return self.a1 + other.a2

    def __enter__(self):
        print(‘1111‘)
        return 999

    def __exit__(self, exc_type, exc_val, exc_tb):
        print(‘22222‘)

1. 类名() 自动执行 __init__
obj = Foo(1,2)

2. 对象() 自动执行 __call__
ret = obj(6,4,2,k1=456)

3. 对象[‘xx‘]  自动执行 __getitem__
ret = obj[‘yu‘]
print(ret)

4. 对象[‘xx‘] = 11  自动执行 __setitem__
obj[‘k1‘] = 123

5. del 对象[xx]     自动执行 __delitem__
del obj[‘uuu‘]

6. 对象+对象         自动执行 __add__
obj1 = Foo(1,2)
obj2 = Foo(88,99)
ret = obj2 + obj1
print(ret)

7. with 对象        自动执行 __enter__ / __exit__
obj = Foo(1,2)
with obj as f:
    print(f)
    print(‘内部代码‘)

8. 真正的构造方法
class Foo(object):
    def __init__(self, a1, a2):     # 初始化方法
        """
        为空对象进行数据初始化
        :param a1:
        :param a2:
        """
        self.a1 = a1
        self.a2 = a2

    def __new__(cls, *args, **kwargs): # 构造方法
        """
        创建一个空对象
        :param args:
        :param kwargs:
        :return:
        """
        return object.__new__(cls) # Python内部创建一个当前类的对象(初创时内部是空的.).

obj1 = Foo(1,2)
print(obj1)

obj2 = Foo(11,12)
print(obj2)