python AttributeError：类XXX没有属性'__class__'

Question

谁能帮我解决这个异常？

File "/root/anaconda2/lib/python2.7/site-packages/numba/dispatcher.py", line 305, in _compile_for_args 
argtypes.append(self.typeof_pyval(a)) 
File "/root/anaconda2/lib/python2.7/site-packages/numba/dispatcher.py", line 429, in typeof_pyval 
    File "/root/anaconda2/lib/python2.7/site-packages/numba/typing/typeof.py", line 28, in typeof 
ty = typeof_impl(val, c) 
File "/root/anaconda2/lib/python2.7/site-packages/singledispatch.py", line 210, in wrapper 
return dispatch(args[0].__class__)(*args, **kw) 
AttributeError: class FeatureEncoding has no attribute '__class__' 

Answer 1

并非每个实例都具有__class__属性。只是一般性建议：在大多数情况下，最好使用type而不是__class__。

例如老式类没有类：

>>> class A: 
... pass 
... 
>>> A.__class__ 
AttributeError: class A has no attribute '__class__' 

>>> int.__class__ # just for comparison the class of the int class 
<type 'type'> 

但type作品：

>>> type(A) 
<type 'classobj'> 

注：旧式的类的实例有__class__属性

>>> a = A() 
>>> a.__class__ 
<class __main__.A at 0x0000000002E61168>