python AttributeError: class XXX has no attribute '__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__。

例如旧式 classes 没有 class:

>>> 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'>

但是 type 有效：

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

注意：旧式 classes 的实例具有 __class__ 属性

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