Devin Jeanpierre jeanpierreda at gmail.com
Mon Apr 23 16:27:40 EDT 2012

• Previous message (by thread): why () is () and [] is [] work in other way?
• Next message (by thread): why () is () and [] is [] work in other way?
• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

---

On Mon, Apr 23, 2012 at 3:58 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
>> Whether a and b are the same object is implementation-dependent.
>
> And that has absolutely nothing to do with the behaviour of "is". The
> "is" operator is not responsible for whether a and b are the same object.

Heh, it has everything to do with the behavior of is. Although I know
what you mean.

> Short of having "is" be a null-op that always returns False, there are no
> changes you can make to the definition of "is" that will make "a is b"
> any more predictable.

Well, no. Immutable objects could always compare equal, for example.
This is more expensive though. is as-it-stands is very quick to
execute, which is probably attractive to some people (especially for
its used in detecting special constants).

-- Devin

---

• Previous message (by thread): why () is () and [] is [] work in other way?
• Next message (by thread): why () is () and [] is [] work in other way?
• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

---

More information about the Python-list mailing list