Python面向对象和类

class Student:
    pass

print(id(Student)) #1149225945800
print(type(Student)) #<class 'type'>
print(Student) #<class '__main__.Student'>

class Student:
    native_place='吉林' #类属性
    def __init__(self,name,age):
        self.name=name
        self.age=age

    #实例方法
    def eat(self):
        print("学生在吃饭")

    #静态方法
    @staticmethod
    def method():
        print("我是静态方法")

    #类方法
    @classmethod
    def cm(cls):
        print("我是类方法")

#实例对象
student1=Student("张三",18)
print(student1)
print(id(student1))
print(type(student1))
print("-------------------------------------------")
#类对象，代表所在的类
print(Student)
print(id(Student))
print(type(Student))

#实例对象
student1=Student("张三",18)

print(student1.name)
print(student1.age)
#实例方法调用有以下两种使用：
print(student1.eat())
print(Student.eat(student1))

#类属性
student1=Student("张三",18)
student2=Student("李四",19)
print(Student.native_place) #吉林
print(student1.native_place)#吉林
print(student2.native_place)#吉林
Student.native_place='四川'
print(student1.native_place)#四川
print(student2.native_place)#四川
#---------------------------------------------------------
student1.native_place='广东'
print(student1.native_place)#广东
print(student2.native_place)#四川

#类方法、静态方法使用
student1=Student("张三",18)

Student.method()#我是静态方法
Student.cm()#我是类方法

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

    #实例方法
    def eat(self):
        print("学生在吃饭")

student1=Student('张三',19)
student2=Student('李四',20)
print(id(student1)) #2363920157896
print(id(student2)) #2363920157960

print("--------绑定属性-------")
print("绑定属性-----为student2动态的绑定gender属性-------")
student2.gender='男'
print(student1.name,student1.age) #张三 19
#print(student1.gender) 当student1访问其没有的属性时，会报错AttributeError: 'Student' object has no attribute 'gender'
print(student2.name,student2.age,student2.gender) #李四 20 男

print("--------绑定方法-------")
def show():
    print('我是show方法')
student1.show=show
student1.show() #我是show方法
student2.show() #报错AttributeError: 'Student' object has no attribute 'show'

class Car:
    def __init__(self,brand,age):
        self.brand=brand
        self.__age=age

    def show(self):
        print(self.brand,self.__age)

car1=Car('宝马X5',50)
print(car1.brand) #宝马X5
# print(car1.__age) __标识的属性限制其在类外使用，在类的内部可以使用，在外面访问是会报错
#若要使用__标识的属性，可以先用dir()查出属性，再访问
print(dir(car1))
#输出['_Car__age', '__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'brand', 'show']
print(car1._Car__age)#50

class People:
    def __init__(self,name,age):
        self.name=name
        self.age=age
    def info(self):
        print(self.name,self.age)

class Student(People):
    def __init__(self,name,age,sno):
        super().__init__(name,age)
        self.sno=sno
class Teacher(People):
    def __init__(self,name,age,teachofage):
        super().__init__(name,age)
        self.teachofage=teachofage

student1=Student('张三',18,122)
teacher1=Teacher('李四',36,10)
student1.info() #张三 18
teacher1.info() #李四 36

class People:
    def __init__(self,name,age):
        self.name=name
        self.age=age
    def info(self):
        print(self.name,self.age)

class Student(People):
    def __init__(self,name,age,sno):
        super().__init__(name,age)
        self.sno=sno
    def info(self):
        super().info()
        print(self.sno)
class Teacher(People):
    def __init__(self,name,age,teachofage):
        super().__init__(name,age)
        self.teachofage=teachofage
    def info(self):
        super().info()
        print(self.teachofage)

student1=Student('张三',18,122)
teacher1=Teacher('李四',36,10)
student1.info() 
teacher1.info()