是否有可能測試對象屬性是否使用描述符？

Question

我不相信這是可能的，但我想我會問，因爲我是新來的Python。給定一個具有屬性的對象，其值由描述符處理;是否有可能知道給定的描述符類型是否涉及？

實施例描述符：

class Column(object): 
    def __init__(self, label): 
     self.label = label 

    def __get__(self, obj, owner): 
     return obj.__dict__.get(self.label) 

    def __set__(self, obj, value): 
     obj.__dict__[self.label] = value 

測試對象：

class Test(object): 
    name = Column("column_name") 

    def add(self): 
     print self.name.__class__ 

執行此：

my_test = Test() 
my_test.name = "myname" 
my_test.add() 

這GIV es：<type 'str'>這是值「myname」的數據類型，是否可以測試isinstance（self.name，Descriptor） - 這將返回false，但我希望它返回true - 或類似的東西？

編輯 - 上Test

Answer 1

舊式類的拆除錯誤搜索對象在方法解析順序類和超類的描述符對象：

def find_descriptor(instance, attrname): 
    '''Find the descriptor handling a given attribute, if any. 

    If the attribute named attrname of the given instance is handled by a 
    descriptor, this will return the descriptor object handling the attribute. 
    Otherwise, it will return None. 

    ''' 

    for klass in type(instance).__mro__: 
     if attrname in klass.__dict__: 
      descriptor = klass.__dict__[attrname] 
      if not (hasattr(descriptor, '__get__') or 
        hasattr(descriptor, '__set__') or 
        hasattr(descriptor, '__delete__')): 
       # Attribute isn't a descriptor 
       return None 
      if (attrname in instance.__dict__ and 
       not hasattr(descriptor, '__set__') and 
       not hasattr(descriptor, '__delete__')): 
       # Would be handled by the descriptor, but the descriptor isn't 
       # a data descriptor and the object has a dict entry overriding 
       # it. 
       return None 
      return descriptor 
    return None