[Python-Dev] Real-world use of Counter

[Ethan Furman]

On 11/05/2014 10:56 AM, Raymond Hettinger wrote:
>
> Please stop using the mailing lists as way to make an end-run around discussions on the tracker.
> http://bugs.python.org/issue22766

You said that without compelling, real-world use cases you don't like to make changes.

The tracker has a very limited audience, while the mailing lists have a much greater chance of reaching the users who 
may actually have the use-cases you would consider.

You call it an end-run, I call it research.


> Also, as asked the question is a bit loaded.  Effectively, it asks "has anyone ever been surprised by an exception
> raised by a duck-typed function or method"?

Actually, it's asking, "Most other duck-typed methods will still raise a TypeError, but these few don't.  Has that ever 
been a problem for you?"


> The in-place operations on counters are duck-typed.  They are intended (by design) to work with ANY type that has an
> items() method.   The exception raised if doesn't have on is an AttributeError saying that the operand needs to have an
> items() method.

It would still be duck-typed with a `hasattr` call on the second operand checking for the necessary method, a TypeError 
could just as easily state the problem is a missing `items()` method, and then those three [*] in-place methods would 
raise the same error as the 20(?) other Counter methods under similar conditions.


> Please let this one die.  It seems to have become your pet project even after I've made a decision and explained my
> rationale.

You indicated you might make a change with sufficient real-world use-cases, so I'm trying to find some.  If none show 
up, I'll let the matter drop.

--
~Ethan~

[*] Amusingly enough, there are four overridden in-place methods:  three raise an AttributeError, but one (&=) still 
raises a TypeError.