property简单使用
1 class P: 2 """ 3 property简单使用 4 """ 5 def __init__(self,name): 6 self._name = name 7 8 @property 9 def name(self): 10 return self._name 11 12 @name.setter 13 def name(self,val): 14 self._name = val 15 16 @name.deleter 17 def name(self): 18 del self._name 19 20 21 p = P("zhangsan") 22 print(p.name) 23 print(p.__dict__) 24 p.name = "wangsi" 25 print(p.name) 26 print(p.__dict__)
结果：
1 zhangsan 2 {'_name': 'zhangsan'} 3 wangsi 4 {'_name': 'wangsi'}
property简单实现
1 class Property: 2 3 def __init__(self,fget=None,fset=None,fdel=None): 4 self.fget = fget 5 self.fset = fset 6 self.fdel = fdel 7 pass 8 9 def __set__(self, instance, value): 10 self.fset(instance,value) 11 return self 12 13 def __get__(self, instance, owner): 14 if not instance: 15 return self 16 return self.fget(instance) 17 18 def __delete__(self, instance): 19 self.fdel(instance) 20 return self 21 22 def setter(self,fn): 23 #保留设置函数的副本 24 self.fset = fn 25 return self 26 27 def deleter(self,fn): 28 # 保留删除函数的副本 29 self.fdel = fn 30 return self 31 32 33 class Person: 34 35 # d = Property() 36 def __init__(self,data): 37 self._data = data 38 39 @Property #等价式 data=Propery(data) 40 def data(self): 41 return self._data 42 43 @data.setter #等价式 data=data.setter(data) 44 def data(self,val): 45 self._data = val 46 47 @data.deleter #等价式 data=data.deleter(data) 48 def data(self): 49 del self._data 50 51 52 p = Person(19) 53 p.data = 123 54 print(Person.__dict__) 55 print(p.__dict__) 56 del p.data 57 print(Person.__dict__) 58 print(p.__dict__)
结果：
1 {'__init__': <function Person.__init__ at 0x0000015F3F0F0598>, '__dict__': <attribute '__dict__' of 'Person' objects>, 'data': <__main__.Property object at 0x0000015F3F0FE240>, '__weakref__': <attribute '__weakref__' of 'Person' objects>, '__module__': '__main__', '__doc__': None} 2 {'_data': 123} 3 {'__init__': <function Person.__init__ at 0x0000015F3F0F0598>, '__dict__': <attribute '__dict__' of 'Person' objects>, 'data': <__main__.Property object at 0x0000015F3F0FE240>, '__weakref__': <attribute '__weakref__' of 'Person' objects>, '__module__': '__main__', '__doc__': None} 4 {}
注意：property 依赖装饰器和数据描述器实现
数据描述器：需要实现__set__()方法和__get__()方法
非数据描述器：需实现__get__()方法