deque is not a subclass of Sequence.

[Rolf Camps]

On 2016-04-07 11:12, Peter Otten wrote:
> Antoon Pardon wrote:
>
>> Second tryal, I hope the formatting doesn't get messed up now
>>
>> Playing around with the collections and collections.abc modules in
>> python3.4 I stumbled upon the following:
>>
>>>>> from collections.abc import Sequence
>>>>> from collections import deque
>>>>> isinstance(list(), Sequence)
>> True
>>>>> isinstance(deque(), Sequence)
>> False
>>
>> This seems strange to me. As far as I understand, the
>> documentation indicates there is no reason why deque
>> shouldn't be a subclass of Sequence.
>>
>> Am I missing something or can this be considered a bug?
>>>> from collections import deque
>>>> from collections.abc import Sequence
>>>> [name for name in set(dir(Sequence)) - set(dir(deque)) if not
> name.startswith("_")]
> ['index']
>
> So the index() method seems to be what is missing.
>
The index method was added to the deque object in Python 3.5.

Python 3.5.1 (default, ...)
[GCC ...] on linux
 >>> import collections
 >>> isinstance(collections.deque(), collections.abc.Sequence)
True