1、封装指的就是把数据与功能都整合到一起
2、在封装的基础上，我可以将装到对象或者类中的属性给隐藏起来
注意：
（1）在定义类或者初始化对象时，在属性前加__,就会将该属性隐藏起来
但该隐藏起始只是一种变形_类名__属性名，并没有真的隐藏起
（2）该变形操作是在类定义阶段扫描语法时发生的变形，类定义之后添加的__开头的属性不会发生变形
（3）该隐藏是对外不对内
（4） 在继承中，父类如果不想让子类覆盖自己的方法，可以将方法定义为私有的？？？
# 例1 # class Student: # __school = "oldboy" # _Student__school = "oldboy" # # def __init__(obj, x, y, z): # obj.__name = x # obj._Student__name = x # obj.age = y # obj.gender = z # # def __choose(self): # obj._Student__choose # print("%s 正在选课" %self.name) # # # stu_obj1 = Student("冯疯子", 18, "female") # stu_obj1.__x=111 # print(stu_obj1.__dict__) # print(stu_obj1.__x) # print(stu_obj1.__dict__) # print(stu_obj1._Student__name) # print(Student.__dict__) # print(Student._Student__school) # print(stu_obj1._Student__school)
隐藏属性的意义
1、把数据属性隐藏起来的意义是：在类内开放接口，让外界使用者通过接口来操作属性值，我们可以在接口之上附加任意的逻辑
来严格控制外界使用者对属性的操作
# class Student: # __school = "oldboy" # _Student__school = "oldboy" # # def __init__(obj, x, y, z): # obj.__name = x # obj._Student__name = x # obj.__age = y # obj.gender = z # # def __choose(self): # obj._Student__choose # print("%s 正在选课" % self.name) # # def get_name(self): # print(self.__name) # print(self._Student__name) # # def set_age(self,x): # if type(x) is not int: # print("年龄必须是整型，傻叉") # return # self.__age = x # # def get_age(self): # print(self.__age) # # def del_age(self): # del self.__age # # stu_obj1 = Student("冯疯子", 18, "female") # # stu_obj1.get_name() # # # # stu_obj1.set_age("asfdasfdasfafd") # stu_obj1.set_age(19) # stu_obj1.get_age() # # print(stu_obj1.__dict__)
2、把功能属性隐藏起来:隔离复杂度
# class ATM: # def __card(self): # print(‘插卡‘) # def __auth(self): # print(‘用户认证‘) # def __input(self): # print(‘输入取款金额‘) # def __print_bill(self): # print(‘打印账单‘) # def __take_money(self): # print(‘取款‘) # # def withdraw(self): # self.__card() # self.__auth() # self.__input() # self.__print_bill() # self.__take_money() # # a=ATM() # a.withdraw()
1、 property
# 例1 # class People: # def __init__(self, name, height, weight): # self.name = name # self.height = height # self.weight = weight # # @property # def bmi(self): # return self.weight / (self.height ** 2) # # # p = People(‘egon‘, 1.81, 70) # p.height = 1.84 # print(p.bmi())
# 例2 # class Student: # __school = "oldboy" # _Student__school = "oldboy" # # def __init__(obj, x, y, z): # obj.__name = x # obj.__age = y # obj.gender = z # # def get_name(self): # print("访问控制") # return self.__name # # def set_name(self,x): # print("赋值控制") # self.__name = x # # def del_name(self): # print("删除控制") # del self.__name # # def get_age(self): # return self.__age # # def set_age(self, x): # if type(x) is not int: # print("年龄必须是整型，傻叉") # return # self.__age = x # # def del_age(self): # print("不让删") # # # age = property(get_age, set_age, del_age) # name = property(get_name, set_name, del_name) # # # stu_obj1 = Student("冯疯子", 18, "female") # # # print(stu_obj1.age) # # stu_obj1.age = "19" # # del stu_obj1.age # # print(stu_obj1.age) # # # print(stu_obj1.name) # # stu_obj1.name="EGON" # # del stu_obj1.name
# 例3: class Student: __school = "oldboy" # _Student__school = "oldboy" def __init__(obj, x, y, z): obj.__name = x obj.__age = y obj.gender = z @property def name(self): print("访问控制") return self.__name @name.setter def name(self, x): print("赋值控制") self.__name = x @name.deleter def name(self): print("删除控制") del self.__name stu_obj1 = Student("冯疯子", 18, "female") stu_obj1.name
2、绑定与非绑定
类中的定义的函数
--- 绑定方法:谁来调用就会将谁当作第一个参数传入
(1)绑定给对象的方法:类中定义的函数默认就是绑定给对象的方法,应该是由对象调用,会把对象当作第一个参数传入
(2)绑定给类的方法:在类中的函数上加一个装饰器@classmethod,该函数就绑定给类了,应该是由类来调用,会把类当作第一个参数传入
---非绑定方法:既不与类绑定也不与对象绑定,就是一个普通的函数,谁都可以来调用,没有自动传参的效果,
在函数上添加装饰器@staticmethod
# class People: # def __init__(self, name, age): # self.name = name # self.age = age # # def tell_info(self): # print("<%s:%s>" % (self.name, self.age)) # # @classmethod # def f1(cls): # print(cls) # # @staticmethod # def f2(x,y,z): # print(x,y,z) # # # p1=People(‘egon‘,18) # # p1.tell_info() # # # print(p1.tell_info) # # print(People.f1) # # # People.f1() # # # print(p1.f2) # # print(People.f2) # p1.f2(1,2,3) # People.f2(1,2,3)
# 例1 import uuid import settings
##sttings里的内容： IP=‘106.78.13‘ PORT=3306 class MySQL: def __init__(self,ip,port): self.mid = self.__create_id() self.ip = ip self.port = port def tell_info(self): print("%s:<%s:%s>" %(self.mid,self.ip,self.port)) @staticmethod def __create_id(): return uuid.uuid4() @classmethod def from_conf(cls): return cls(settings.IP, settings.PORT) # obj = MySQL("10.10.11.11",3306) # obj.tell_info() obj1=MySQL.from_conf() obj1.tell_info()
面向对象编程之——封装，装饰器（property,classmethod,staticmethod）
原文：https://www.cnblogs.com/guojieying/p/13441975.html