Re: [newbie] A question about lists and strings

References	(1 earlier) <39A401F0-12DD-464F-A0D1-639C56FA48A0@gmail.com> <mailman.3148.1344592099.4697.python-list@python.org> <k02mpk$p0e$1@news.albasani.net> <CAPTjJmrabsW3w8WNqDNeGU8f5rc0Kq0U83Vd7To7sX-SOWWtew@mail.gmail.com> <5024E8CC.9020703@davea.name>
Date	2012-08-10 21:00 +1000
Subject	Re: [newbie] A question about lists and strings
From	Chris Angelico <rosuav@gmail.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.3158.1344596443.4697.python-list@python.org> (permalink)

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On Fri, Aug 10, 2012 at 8:56 PM, Dave Angel <d@davea.name> wrote:
>> On Fri, Aug 10, 2012 at 8:07 PM, Dave Angel <d@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

Thread

[newbie] A question about lists and strings Mok-Kong Shen <mok-kong.shen@t-online.de> - 2012-08-10 11:19 +0200
  Re: [newbie] A question about lists and strings Roman Vashkevich <vashkevichrb@gmail.com> - 2012-08-10 13:28 +0400
  Re: [newbie] A question about lists and strings Roman Vashkevich <vashkevichrb@gmail.com> - 2012-08-10 13:48 +0400
    Re: [newbie] A question about lists and strings Mok-Kong Shen <mok-kong.shen@t-online.de> - 2012-08-10 12:12 +0200
      Re: [newbie] A question about lists and strings Chris Angelico <rosuav@gmail.com> - 2012-08-10 20:37 +1000
      Re: [newbie] A question about lists and strings Dave Angel <d@davea.name> - 2012-08-10 06:37 -0400
      Re: [newbie] A question about lists and strings Roman Vashkevich <vashkevichrb@gmail.com> - 2012-08-10 14:56 +0400
        Re: [newbie] A question about lists and strings Mok-Kong Shen <mok-kong.shen@t-online.de> - 2012-08-10 13:08 +0200
      Re: [newbie] A question about lists and strings Dave Angel <d@davea.name> - 2012-08-10 06:56 -0400
      Re: [newbie] A question about lists and strings Chris Angelico <rosuav@gmail.com> - 2012-08-10 21:00 +1000
      Re: [newbie] A question about lists and strings Roman Vashkevich <vashkevichrb@gmail.com> - 2012-08-10 15:06 +0400
  Re: [newbie] A question about lists and strings Peter Otten <__peter__@web.de> - 2012-08-10 11:59 +0200
    Re: [newbie] A question about lists and strings Rotwang <sg552@hotmail.co.uk> - 2012-08-10 16:12 +0100
  Re: [newbie] A question about lists and strings Dave Angel <d@davea.name> - 2012-08-10 06:07 -0400
    Re: [newbie] A question about lists and strings Mok-Kong Shen <mok-kong.shen@t-online.de> - 2012-08-10 12:31 +0200
      Re: [newbie] A question about lists and strings Chris Angelico <rosuav@gmail.com> - 2012-08-10 20:40 +1000
        Re: [newbie] A question about lists and strings Mok-Kong Shen <mok-kong.shen@t-online.de> - 2012-08-10 12:48 +0200
          Re: [newbie] A question about lists and strings Dave Angel <d@davea.name> - 2012-08-10 06:58 -0400
      Re: [newbie] A question about lists and strings Dave Angel <d@davea.name> - 2012-08-10 06:53 -0400

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