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Re: Building CPython

References (4 earlier) <zR85x.441429$Zf4.246168@fx22.am4> <xpb5x.597872$X95.548374@fx10.am4> <crlglfFgf05U1@mid.individual.net> <87bnhmgqrx.fsf@elektro.pacujo.net> <5555c708$0$13009$c3e8da3$5496439d@news.astraweb.com>
Date 2015-05-15 20:25 +1000
Subject Re: Building CPython
From Chris Angelico <rosuav@gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.32.1431685525.17265.python-list@python.org> (permalink)

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On Fri, May 15, 2015 at 8:14 PM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> (If anything, using an implicit boolean test will be faster than an
> explicit manual test, because it doesn't have to call the len() global.)

Even more so: Some objects may be capable of determining their own
lengths, but can ascertain their own emptiness more quickly. So len(x)
might have to chug chug chug to figure out exactly how many results
there are (imagine a database query or something), where bool(x)
merely has to see whether or not a single one exists (imagine a
database query with "LIMIT 1" tacked on).

ChrisA

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Thread

Building CPython BartC <bc@freeuk.com> - 2015-05-13 20:36 +0100
  Re: Building CPython Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-13 20:58 +0100
  Re: Building CPython Terry Reedy <tjreedy@udel.edu> - 2015-05-13 18:34 -0400
    Re: Building CPython BartC <bc@freeuk.com> - 2015-05-14 16:51 +0100
      Re: Building CPython Chris Angelico <rosuav@gmail.com> - 2015-05-15 02:09 +1000
        Re: Building CPython BartC <bc@freeuk.com> - 2015-05-14 18:02 +0100
          Re: Building CPython Dave Angel <davea@davea.name> - 2015-05-14 13:10 -0400
          Re: Building CPython Chris Angelico <rosuav@gmail.com> - 2015-05-15 03:11 +1000
            Re: Building CPython BartC <bc@freeuk.com> - 2015-05-14 18:32 +0100
              Re: Building CPython Chris Angelico <rosuav@gmail.com> - 2015-05-15 03:45 +1000
          Re: Building CPython Terry Reedy <tjreedy@udel.edu> - 2015-05-14 14:50 -0400
            Re: Building CPython Christian Gollwitzer <auriocus@gmx.de> - 2015-05-15 12:51 +0200
              Re: Building CPython Terry Reedy <tjreedy@udel.edu> - 2015-05-15 17:19 -0400
      Re: Building CPython Marko Rauhamaa <marko@pacujo.net> - 2015-05-14 19:29 +0300
        Re: Building CPython BartC <bc@freeuk.com> - 2015-05-14 22:55 +0100
          Re: Building CPython MRAB <python@mrabarnett.plus.com> - 2015-05-14 23:19 +0100
          Re: Building CPython BartC <bc@freeuk.com> - 2015-05-15 01:50 +0100
            Re: Building CPython Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-05-15 18:05 +1200
              Re: Building CPython Marko Rauhamaa <marko@pacujo.net> - 2015-05-15 11:59 +0300
                Re: Building CPython wxjmfauth@gmail.com - 2015-05-15 02:07 -0700
                Re: Building CPython Marko Rauhamaa <marko@pacujo.net> - 2015-05-15 12:20 +0300
                Re: Building CPython wxjmfauth@gmail.com - 2015-05-15 02:51 -0700
                Re: Building CPython Marko Rauhamaa <marko@pacujo.net> - 2015-05-15 13:52 +0300
                Re: Building CPython Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-15 22:10 +1000
                Re: Building CPython Chris Angelico <rosuav@gmail.com> - 2015-05-15 22:34 +1000
                Re: Building CPython wxjmfauth@gmail.com - 2015-05-15 07:11 -0700
                Re: Building CPython Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-15 13:41 +0100
                Re: Building CPython Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-15 13:38 +0100
                Re: Building CPython Chris Angelico <rosuav@gmail.com> - 2015-05-15 19:43 +1000
                Re: Building CPython Marko Rauhamaa <marko@pacujo.net> - 2015-05-15 13:50 +0300
                Re: Building CPython Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-15 22:43 +1000
                Re: Building CPython Ian Kelly <ian.g.kelly@gmail.com> - 2015-05-15 09:00 -0600
                Re: Building CPython Ian Kelly <ian.g.kelly@gmail.com> - 2015-05-15 09:04 -0600
                Re: Building CPython Chris Angelico <rosuav@gmail.com> - 2015-05-16 01:06 +1000
                Re: Building CPython Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-15 20:14 +1000
                Re: Building CPython Chris Angelico <rosuav@gmail.com> - 2015-05-15 20:25 +1000
                Re: Building CPython Terry Reedy <tjreedy@udel.edu> - 2015-05-15 17:05 -0400
                Re: Building CPython BartC <bc@freeuk.com> - 2015-05-15 22:54 +0100
                Re: Building CPython Marko Rauhamaa <marko@pacujo.net> - 2015-05-16 01:44 +0300
                Re: Building CPython Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-16 00:27 +0100
                Re: Building CPython Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-16 11:55 +1000
                Re: Building CPython Chris Angelico <rosuav@gmail.com> - 2015-05-16 12:15 +1000
                Re: Building CPython Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-16 03:17 +0100
                Re: Building CPython BartC <bc@freeuk.com> - 2015-05-16 01:43 +0100
                Re: Building CPython MRAB <python@mrabarnett.plus.com> - 2015-05-16 02:16 +0100
                Re: Building CPython Marko Rauhamaa <marko@pacujo.net> - 2015-05-16 11:08 +0300
                Re: Building CPython Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-16 19:40 +1000
                Re: Building CPython Marko Rauhamaa <marko@pacujo.net> - 2015-05-16 16:59 +0300
                Re: Building CPython Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-17 04:18 +1000
                Re: Building CPython Marko Rauhamaa <marko@pacujo.net> - 2015-05-16 21:55 +0300
                Re: Building CPython Marko Rauhamaa <marko@pacujo.net> - 2015-05-17 01:51 +0300
                Re: Building CPython Marko Rauhamaa <marko@pacujo.net> - 2015-05-17 23:49 +0300
                Re: Building CPython Terry Reedy <tjreedy@udel.edu> - 2015-05-15 19:54 -0400
              Re: Building CPython BartC <bc@freeuk.com> - 2015-05-15 10:32 +0100
                Re: Building CPython Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-05-16 12:55 +1200
                Re: Building CPython Jonas Wielicki <jonas@wielicki.name> - 2015-05-17 14:25 +0200
                Re: Building CPython BartC <bc@freeuk.com> - 2015-05-17 14:41 +0100

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