内容概要
- 案例
- 绑定方法
- 非绑定方法（静态方法）
- 如何隐藏属性
- property装饰器
内容详细
案例
题目：
1. 定义一个类，产生一堆对象
2. 统计产生了多少个对象
'''思路：定义一个计数器，每产生一个对象，计数器加1'''
class Student():
school = 'SH'
count = 0 # 专门用来计数
def __init__(self, name, age):
# self => stu => {'name':'ly', 'age': 18, 'count'：1}
# self => stu1 => {'name':'ly1', 'age': 18, 'count'：1}
# self => stu2 => {'name':'ly2', 'age': 18, 'count'：1}
self.name = name
self.age = age
# self.count = self.count + 1
# Student.count += 1
# self.__class__ # Student
self.__class__.count += 1
绑定方法
绑定方法分为2种：
1. 绑定给对象的
class Student():
def __init__(self, name, age, gender):
self.name = name
self.age = age
self.gender = gender
# 绑定给对象的方法，对象来调用，会把自己当成第一个参数传到函数里面self
def tell_info(self):
print('name: %s，age:%s, gender:%s' % (self.name, self.age, self.gender))
stu = Student('ly', 18, 'male')
# print(stu.name)
stu.tell_info() # stu.tell_info(stu)
2. 绑定给类的
class Mysql():
def __init__(self, ip, port):
self.ip = ip
self.port = port
@classmethod # 该方法绑定给类了，以后有类来调用，会自动把类名当成第一个参数传过来，cls
def from_conf(cls):
# cls => Oracle
# obj = Oracle(settings.IP, settings.PORT)
obj = cls(settings.IP, settings.PORT)
return obj
Mysql.from_conf()
非绑定方法
# 既不绑定给类，也不绑定给对象
class Student():
school = 'SH'
def __init__(self, name, age):
self.name = name
self.age = age
@staticmethod # 静态方法
def create_id():
import uuid
return uuid.uuid4()
stu = Student('ly', 18)
# print(stu.create_id())
# print(Student.create_id())
print(stu.create_id())
如何隐藏属性
# 1. 如何隐藏
# 1. 如何隐藏
'''
1. 在类定义阶段，发生了语法上的变形_类名__属性名
2. 隐藏对外不对内
3. 只有在类定义阶段发生变形，其他情况都不发生变形了
为什么要隐藏: 类里面的隐藏属性， 类外部可以使用，但是目的不是让类外部使用的，类外部要是想用，在类内部开放接口进行访问
可以达到对外部数据的严格控制
'''
class Student():
__school = 'SH' # _Student__school => _类名__属性名
def __init__(self, name, age):
self.__name = name
self.age = age
def __tell_info(self): # _Student__tell_info => _类名__函数名
print('name: %s, age: %s' % (self.__name, self.age))
def get_school(self):
return self.__school # self._Student__school
def set_school(self, v):
if type(v) is not str:
print('数据类型不合法')
# if isinstance(v, str):
return
self.__school = v
# 2. 为何隐藏
property装饰器
class Student():
__school = 'SH' # _Student__school => _类名__属性名
def __init__(self, name, age):
self.__name = name
self.age = age
def __tell_info(self): # _Student__tell_info => _类名__函数名
print('name: %s, age: %s' % (self.__name, self.age))
@property # 把方法伪装成属性
def name(self):
return "name:%s" % self.__name
@name.setter
def name(self, v):
if type(v) is not str:
print('数据类型不合法')
# if isinstance(v, str):
return
self.__name = v
@name.deleter
def name(self):
print('不让删')
stu = Student('ly', 18)
print(stu.get_name())
stu.name = 123
print(stu.name)
del stu.name
# 练习
class Bmi():
def __init__(self, height, weight):
self.height = height
self.weight = weight
@property
def get_bmi(self):
return self.weight / (self.height ** 2)
bmi = Bmi(1.8, 70)
print(bmi.get_bmi)
# 了解
class Student():
__school = 'SH' # _Student__school => _类名__属性名
def __init__(self, name, age):
self.__name = name
self.age = age
def __tell_info(self): # _Student__tell_info => _类名__函数名
print('name: %s, age: %s' % (self.__name, self.age))
def get_name(self):
return "name:%s" % self.__name
def set_name(self, v):
if type(v) is not str:
print('数据类型不合法')
# if isinstance(v, str):
return
self.__name = v
def del_name(self):
print('不让删')
# 了解
name = property(get_name, set_name, del_name)
stu = Student('ly', 18)
# print(stu.xxx)
stu.name = 'aaa'
print(stu.name)
