[newbie] A question about lists and strings

[Chris Angelico]

On Fri, Aug 10, 2012 at 8:56 PM, Dave Angel <d at davea.name> wrote:
>> On Fri, Aug 10, 2012 at 8:07 PM, Dave Angel <d at davea.name> wrote:
>>> But if you said  c=651 and d=651, you'd have two
>>> objects, and the two names would be bound to different objects, with
>>> different ids.
>> To be more accurate, you *may* have two different objects. It's
>> possible for things to be optimized (eg with small numbers, or with
>> constants compiled at the same time).
>
> You're right, of course.  But I picked the value of 650+ deliberately,
> as I believe CPython doesn't currently optimize ints over 256.

Yep. Also:

>>> a=651; b=651
>>> a is b
True
>>> a=651
>>> a is b
False

Same thing occurs (or at least, appears to) with constants in the same
module. Could potentially be a fairly hefty optimization, if you use
the same numbers all the time (bit flags, scale factors, modulo
divisors, etc, etc, etc).

Still doesn't alter your fundamental point of course.

ChrisA