[Python-Dev] unsubscriptable vs object does not support indexing

[Janzert]

Steven D'Aprano wrote:
> On Thu, 24 Sep 2009 06:47:41 am Dino Viehland wrote:
>>> So I am +1 on unified the message and +1 on using the "does not
>>> support indexing" one.
>> I'd be +1 on the unified message as well - but it seems what that
>> message should be may be contentious (and quite a bike shed
>> discussion at that). The bug David linked to
>> (http://bugs.python.org/issue5760) has a preference for subscript
>> because that's what's used elsewhere in the language.
> 
> For what it's worth, "unsubscriptable object" seems to me to be 
> mysterious to many newbies, and even a few non-newbies. It took me 
> something like seven years of coding to stop reading it 
> as "unscriptable object", and I'm sure I won't be the only one.
> 
> As far as I can see, in practice, people talk about obj[i] as the item 
> at index i, not the item at subscript i -- the term "subscript" in this 
> context seems to be rare to non-existent except for the error message.
> 
> 
> 

How about if it's obj["item"]? To me the following makes complete sense,
but then it seems that I may just be the odd one out.

>>> class A(object):
...     pass
...
>>> a = A()
>>> a[1]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'A' object is unindexable
>>> a["a"]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'A' object is unsubscriptable
>>>

Janzert