Python面向对象的内置方法梳理讲解

class Student:
    def __init__(self,name,age):
        self.name = name
        self.age = age
stu1 = Student('xiaoming',18)
print(stu1)      #运行原理就是，先在Student类里找__str__方法，没有就去他的父类找
print(object.__str__(stu1))   #验证了Student的父类里面有__str__方法

class Student:
    def __init__(self,name,age):
        self.name = name
        self.age = age
    def __str__(self):
        print(self.name)
        return '<name:%s age:%s>' %(self.name,self.age)
stu1 = Student('xiaoming',18)
print(stu1)     #这个stu1就是__str__的返回值

class Student:
    def __init__(self, name, age):
        self.name = name
        self.age = age
    def __del__(self):
        print('%s 已经被删除' % self.name)
stu1 = Student('xiaoming', 18)
stu2 = Student('zhangsan', 18)
print('主')

class Student:   #补充：class Student: 相当于就是 Student = type(类名,该类的基类们,类体代码产生的名称空间)
    pass
Student()

class Student:  # (相当于上面例子的type)
    def __init__(self, name, age):
        self.name = name
        self.age = age
stu1 = Student('xiaoming', 18)  # stu1(相当于上面例子的Student)
try:  # 这里我们通过捕捉异常来打印出错原因
    stu1()  # 这里相当于上面Student()
except Exception as e:
    print(e)
    # 打印结果是：'Student' object is not callable
    # “Student”对象不可调用，也就是stu1是不可调用的

class Teacher:
    def __init__(self, name):
        self.name = name
    def __call__(self, *args, **kwargs):
        print('我被%s调用了' % self.name)
tea1 = Teacher('xiaoming')
tea1()

class Mymeta(type):
    def __call__(self, *args, **kwargs):  # self就是Student *args和**kwargs就是Student后面的参数
        # print(self)
        # print(args)
        # print(kwargs)
        obj = self.__new__(self)  # 就是创建一个Student的空对象
        self.__init__(obj, *args, **kwargs)  # 执行__init__方法    这里需要注意查找顺序
        return obj  # 将实例化完的对象返回回去
class Student(object, metaclass=Mymeta):
    def __init__(self, name, age):
        self.name = name
        self.age = age
stu1 = Student('xiaoming', age=18)
print(type(stu1),stu1.__dict__)