Python--property (Make a method look like a class property)

Tag:format    No    app    change     code      exception    hello   elf   int   

"" "Adorner property:     makes a method look like a class property" "" #例子1class  a:    def __ Init__ (self,  x, y):         self.__x = x   #私有变量         self.__y = y    def  __add (self):  #私有方法         return self.__x +  self.__y     @property     def sum (self):  # When modified with the property adorner, the method looks like an attribute         return self.__add () if __ name__ ==  ' __main__ ':     a = a (5,6)     print (a.sum   #外部调用sum, it looks like a property, this property is actually a method that does not function in the calculation # example 2class foo:     @property      def foo (self):        return  "bar" f =  Foo () print (F.foo) Example 3class foo:     @property     def foo (self):         return self._foo     @foo .setter  #使用foo方法的setter属性又装饰了这个foo方法, This foo and the above Foo are just the same name, actually different     def foo (Self, value):         self._foo = valuef = foo () f.foo = 100print (F.foo) #一定要注意了, The function that is decorated by the property decorator returns an Object # example 4class silly:     @property     def  silly (self):         print ("you are getting silly" )         return self._silly  #返回的是一个property对象       @silly. setter    def silly (Self, value):         print ("you are making silly {}". Format (value))          self._silly = value     @silly .deleter  #删除函数 (currently I don't know how to use it)      def silly (self):         print ("whoah you killed  silly! ")         del self._sillys = Sillys.silly =  100print (s.silly) #再看最后的一个例子, a price attribute in an Apple class class apple:    def __init__ (self,  Price):         self.price = pricea = apple (19) Print (A.price) a.price = 20  #随意被更改了, there is a data security issue print (A.price) #改进代码v1 .0class apple:     def __init__ (self, price):         self._price  = price  #将属性增加单下划线, turn semi-protected a = apple   #初始化价格print (a._price)   # Print a.price = 25  #尝试的修改print (a._price)   #貌似没有修改成功, or the original 19# continue to improve  v1.0.1class apple:     d ef __init__ (Self, price):        self._price =  Pricea = apple ("Hello")   #price是价格, but being passed in is a string, which means that data that is randomly passed into different data types needs to continue to improve print (A._price) #继续改进  v1.0.2class apple (object):     def get_price (self):         return self.__price    def set_score (Self, price):         if not isinstance (Price, int):             raise valueerror (' Price must be  an integer! ')         self.__price = pricea = apple () A.set_score   #那么可以再试试传入字符串, the exception is thrown by print (A.get_price ()) #最终版本  v2.0class apple (object):      @property     def get_price (self):        & nbsp;try:            return self.__price         except AttributeError:             print ("No data ...")      @get_price. setter #@ The property itself creates another adorner @get_price.setter, which is responsible for turning a setter method into an attribute assignment     def set_score (self,  price):         if not isinstance (Price, int):             raise valueerror (' Price must  be an integer! ')         self.__price = pricea = apple () A.set_score  = 20print (A.get_price)

Python--property (Make a method look like a class property)