类的初始化与回调的用法

学习目标：

正确区分类的初始化与回调

有关类的初始化

class A():
    def __init__(self):
        print('Hello， world！')
A()

有关类的调用

class A():
    def __call__(self):
        print('hello,world!!!!!!!!!!!!!!')
a = A()
a()

这就是__init__与__call__在用法上的区别！

关于二者在编程中具体应用

示例一

class A():
    def __init__(self):
        print('hello,world!')

    def __call__(self):
        print('hello,world!!!!!!!!!!!!!')
a = A()
a()

示例二

class A():
    def __init__(self, init_age):
        print('我年龄是:', init_age)
        self.age = init_age
    def __call__(self, added_age):
        res = self.forward(added_age)  #调用forward函数
        return res
    def forward(self, input_):
        print('forward 函数被调用了')
        return input_ + self.age
print('对象初始化………………')
a = A(16)
input_param = a(2)
print("我现在的年龄永远是：", input_param)

示例三

class Animal():
    def __init__(self,name):
        self.name = name
    def greet(self):
        print('animal is {}'.format(self.name))
class Cat(Animal):
    def greet(self):
        super(Cat, self).greet()
        print("It's name is wangwang")
a=Cat('cat')
a.greet()

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