Re: RE Module Performance

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Date	2013-07-25 04:15 +1000
Subject	Re: RE Module Performance
From	Chris Angelico <rosuav@gmail.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.5059.1374689751.3114.python-list@python.org> (permalink)

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On Thu, Jul 25, 2013 at 3:52 AM, Terry Reedy <tjreedy@udel.edu> wrote:
> On 7/24/2013 11:00 AM, Michael Torrie wrote:
>>
>> On 07/24/2013 08:34 AM, Chris Angelico wrote:
>>>
>>> Frankly, Python's strings are a *terrible* internal representation
>>> for an editor widget - not because of PEP 393, but simply because
>>> they are immutable, and every keypress would result in a rebuilding
>>> of the string. On the flip side, I could quite plausibly imagine
>>> using a list of strings;
>
>
> I used exactly this, a list of strings, for a Python-coded text-only mock
> editor to replace the tk Text widget in idle tests. It works fine for the
> purpose. For small test texts, the inefficiency of immutable strings is not
> relevant.
>
> Tk apparently uses a C-coded btree rather than a Python list. All details
> are hidden, unless one finds and reads the source ;-), but but it uses C
> arrays rather than Python strings.
>
>
>>> In this usage, the FSR is beneficial, as it's possible to have
>>> different strings at different widths.
>
>
> For my purpose, the mock Text works the same in 2.7 and 3.3+.

Thanks for that report! And yes, it's going to behave exactly the same
way, because its underlying structure is an ordered list of ordered
lists of Unicode codepoints, ergo 3.3/PEP 393 is merely a question of
performance. But if you put your code onto a narrow build, you'll have
issues as seen below.

>> Maybe, but simply thinking logically, FSR and UCS-4 are equivalent in
>> pros and cons,
>
> They both have the pro that indexing is direct *and correct*. The cons are
> different.

They're close enough, though. It's simply a performance tradeoff - use
the memory all the time, or take a bit of overhead to give yourself
the option of using less memory. The difference is negligible compared
to...

>> and the cons of using UCS-2 (the old narrow builds) are
>> well known.  UCS-2 simply cannot represent all of unicode correctly.
>
> Python's narrow builds, at least for several releases, were in between USC-2
> and UTF-16 in that they used surrogates to represent all unicodes but did
> not correct indexing for the presence of astral chars. This is a nuisance
> for those who do use astral chars, such as emotes and CJK name chars, on an
> everyday basis.

... this. If nobody had ever thought of doing a multi-format string
representation, I could well imagine the Python core devs debating
whether the cost of UTF-32 strings is worth the correctness and
consistency improvements... and most likely concluding that narrow
builds get abolished. And if any other language (eg ECMAScript)
decides to move from UTF-16 to UTF-32, I would wholeheartedly support
the move, even if it broke code to do so. To my mind, exposing UTF-16
surrogates to the application is a bug to be fixed, not a feature to
be maintained. But since we can get the best of both worlds with only
a small amount of overhead, I really don't see why anyone should be
objecting.

ChrisA

Thread

RE Module Performance Devyn Collier Johnson <devyncjohnson@gmail.com> - 2013-07-11 19:44 -0400
  Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-12 02:23 -0700
    Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-12 19:27 +1000
    Re: RE Module Performance Joshua Landau <joshua@landau.ws> - 2013-07-12 10:39 +0100
    Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-12 19:40 +1000
    Re: RE Module Performance Devyn Collier Johnson <devyncjohnson@gmail.com> - 2013-07-12 06:45 -0400
    Re: RE Module Performance Joshua Landau <joshua@landau.ws> - 2013-07-12 16:59 +0100
    Re: RE Module Performance Peter Otten <__peter__@web.de> - 2013-07-12 18:15 +0200
    Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-13 02:21 +1000
    Re: RE Module Performance Devyn Collier Johnson <devyncjohnson@gmail.com> - 2013-07-12 13:58 -0400
      Re: RE Module Performance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-13 05:37 +0000
        Re: RE Module Performance 88888 Dihedral <dihedral88888@gmail.com> - 2013-07-14 11:17 -0700
          Re: RE Module Performance Devyn Collier Johnson <devyncjohnson@gmail.com> - 2013-07-15 06:06 -0400
            Re: RE Module Performance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-15 12:36 +0000
              Dihedral Devyn Collier Johnson <devyncjohnson@gmail.com> - 2013-07-15 08:52 -0400
              Re: Dihedral Joel Goldstick <joel.goldstick@gmail.com> - 2013-07-15 09:03 -0400
              Re: Dihedral Wayne Werner <wayne@waynewerner.com> - 2013-07-15 17:43 -0500
              Re: Dihedral Fábio Santos <fabiosantosart@gmail.com> - 2013-07-15 23:54 +0100
              Re: Dihedral Chris Angelico <rosuav@gmail.com> - 2013-07-16 08:59 +1000
              Re: Dihedral Tim Delaney <timothy.c.delaney@gmail.com> - 2013-07-16 16:06 +1000
              Re: Dihedral Stefan Behnel <stefan_ml@behnel.de> - 2013-07-24 20:08 +0200
              Re: Dihedral Chris Angelico <rosuav@gmail.com> - 2013-07-25 04:23 +1000
              Re: Dihedral Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-07-24 20:15 -0400
    Re: RE Module Performance Tim Delaney <timothy.c.delaney@gmail.com> - 2013-07-13 08:16 +1000
    Re: RE Module Performance Michael Torrie <torriem@gmail.com> - 2013-07-12 17:13 -0600
      Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-24 06:40 -0700
        Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-24 23:48 +1000
        Re: RE Module Performance David Hutto <dwightdhutto@gmail.com> - 2013-07-24 10:17 -0400
        Re: RE Module Performance David Hutto <dwightdhutto@gmail.com> - 2013-07-24 10:19 -0400
        Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-25 00:34 +1000
          Re: RE Module Performance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-25 07:02 +0000
            Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-25 17:39 +1000
        Re: RE Module Performance Michael Torrie <torriem@gmail.com> - 2013-07-24 08:47 -0600
          Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-25 02:27 -0700
            Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-25 20:14 +1000
              Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-25 12:07 -0700
                Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-26 05:18 +1000
                RE: RE Module Performance "Prasad, Ramit" <ramit.prasad@jpmorgan.com> - 2013-07-25 19:30 +0000
                Re: RE Module Performance Michael Torrie <torriem@gmail.com> - 2013-07-25 21:06 -0600
        Re: RE Module Performance Michael Torrie <torriem@gmail.com> - 2013-07-24 09:00 -0600
          Re: RE Module Performance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-25 05:56 +0000
        Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-25 00:56 +1000
        Re: RE Module Performance Terry Reedy <tjreedy@udel.edu> - 2013-07-24 13:52 -0400
        Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-25 04:15 +1000
          Re: RE Module Performance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-25 07:15 +0000
            Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-25 17:58 +1000
              Re: RE Module Performance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-25 09:22 +0000
                Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-25 20:07 +1000
        Re: RE Module Performance Terry Reedy <tjreedy@udel.edu> - 2013-07-24 18:09 -0400
        Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-25 08:19 +1000
        Re: RE Module Performance Michael Torrie <torriem@gmail.com> - 2013-07-24 16:59 -0600
        Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-25 09:24 +1000
        Re: RE Module Performance Serhiy Storchaka <storchaka@gmail.com> - 2013-07-25 08:49 +0300
        Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-25 15:58 +1000
        Re: RE Module Performance Jeremy Sanders <jeremy@jeremysanders.net> - 2013-07-25 14:36 +0100
          Re: RE Module Performance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-25 15:26 +0000
            Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-26 01:36 +1000
              Re: RE Module Performance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-25 17:18 +0000
                Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-26 03:27 +1000
                Re: RE Module Performance Ian Kelly <ian.g.kelly@gmail.com> - 2013-07-25 15:45 -0500
                Re: RE Module Performance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-26 02:48 +0000
                Re: RE Module Performance Ian Kelly <ian.g.kelly@gmail.com> - 2013-07-25 21:20 -0600
                Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-26 06:36 -0700
                Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-26 08:46 -0700
                Re: RE Module Performance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-27 06:28 +0000
                Re: RE Module Performance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-27 03:37 +0000
                Re: RE Module Performance Ian Kelly <ian.g.kelly@gmail.com> - 2013-07-26 22:12 -0600
                Re: RE Module Performance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-27 05:04 +0000
                Re: RE Module Performance Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-07-27 12:13 -0400
                Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-26 06:19 -0700
                Re: RE Module Performance Michael Torrie <torriem@gmail.com> - 2013-07-25 21:09 -0600
                Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-26 06:21 -0700
                Re: RE Module Performance Michael Torrie <torriem@gmail.com> - 2013-07-26 20:05 -0600
                Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-27 11:21 -0700
                Re: RE Module Performance Ian Kelly <ian.g.kelly@gmail.com> - 2013-07-27 21:53 -0600
                Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-28 11:13 -0700
                Re: RE Module Performance MRAB <python@mrabarnett.plus.com> - 2013-07-28 20:04 +0100
                Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-28 12:30 -0700
                Re: RE Module Performance Lele Gaifax <lele@metapensiero.it> - 2013-07-28 22:45 +0200
                Re: RE Module Performance Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-07-28 22:01 +0200
                Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-30 07:01 -0700
                Re: RE Module Performance Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-07-30 16:38 +0200
                Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-30 15:45 +0100
                Re: RE Module Performance MRAB <python@mrabarnett.plus.com> - 2013-07-30 17:13 +0100
                Re: RE Module Performance Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-07-30 18:39 +0200
                Re: RE Module Performance MRAB <python@mrabarnett.plus.com> - 2013-07-30 18:14 +0100
                Re: RE Module Performance Neil Hodgson <nhodgson@iinet.net.au> - 2013-07-31 13:09 +1000
                Re: RE Module Performance Tim Delaney <timothy.c.delaney@gmail.com> - 2013-07-31 03:27 +1000
                Re: RE Module Performance Joshua Landau <joshua@landau.ws> - 2013-07-30 18:40 +0100
                Re: RE Module Performance Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-07-30 20:19 +0200
                Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-30 12:09 -0700
                Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-30 21:04 +0100
                Re: RE Module Performance Michael Torrie <torriem@gmail.com> - 2013-07-30 21:54 -0600
                Re: RE Module Performance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-31 05:45 +0000
                Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-31 08:17 +0100
                Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-31 13:15 -0700
                Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-31 21:41 +0100
                Re: RE Module Performance Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-07-31 10:11 +0200
                Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-31 01:32 -0700
                Re: RE Module Performance Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-07-31 10:59 +0200
                Re: RE Module Performance Michael Torrie <torriem@gmail.com> - 2013-07-31 08:44 -0600
                Re: RE Module Performance Terry Reedy <tjreedy@udel.edu> - 2013-07-30 17:05 -0400
                Re: RE Module Performance Michael Torrie <torriem@gmail.com> - 2013-07-30 21:30 -0600
                Re: RE Module Performance Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-07-31 09:23 +0200
                Re: RE Module Performance Michael Torrie <torriem@gmail.com> - 2013-07-31 08:27 -0600
                Re: RE Module Performance Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-07-28 10:45 +0200
                FSR and unicode compliance - was Re: RE Module Performance Michael Torrie <torriem@gmail.com> - 2013-07-28 09:52 -0600
                Re: FSR and unicode compliance - was Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-28 12:23 -0700
                Re: FSR and unicode compliance - was Re: RE Module Performance MRAB <python@mrabarnett.plus.com> - 2013-07-28 20:44 +0100
                Re: FSR and unicode compliance - was Re: RE Module Performance Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-07-28 21:55 +0200
                Re: FSR and unicode compliance - was Re: RE Module Performance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-28 20:52 +0000
                Re: FSR and unicode compliance - was Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-29 04:43 -0700
                Re: FSR and unicode compliance - was Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-29 12:57 +0100
                Re: FSR and unicode compliance - was Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-29 05:56 -0700
                Re: FSR and unicode compliance - was Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-29 07:20 -0700
                Re: FSR and unicode compliance - was Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-29 15:49 +0100
                Re: FSR and unicode compliance - was Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-29 09:31 -0700
                Re: FSR and unicode compliance - was Re: RE Module Performance Heiko Wundram <modelnine@modelnine.org> - 2013-07-29 14:06 +0200
                Re: FSR and unicode compliance - was Re: RE Module Performance Devyn Collier Johnson <devyncjohnson@gmail.com> - 2013-07-29 08:43 -0400
                Re: FSR and unicode compliance - was Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-28 18:03 +0100
                Re: FSR and unicode compliance - was Re: RE Module Performance Terry Reedy <tjreedy@udel.edu> - 2013-07-28 13:36 -0400
                Re: FSR and unicode compliance - was Re: RE Module Performance wxjmfauth@gmail.com - 2013-07-29 06:36 -0700
                Re: FSR and unicode compliance - was Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-28 19:03 +0100
                Re: RE Module Performance Joshua Landau <joshua@landau.ws> - 2013-07-28 19:19 +0100
                Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-28 19:29 +0100
                Re: RE Module Performance Terry Reedy <tjreedy@udel.edu> - 2013-07-28 15:06 -0400
                Re: RE Module Performance Joshua Landau <joshua@landau.ws> - 2013-07-28 23:14 +0100
                Re: RE Module Performance Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-07-28 20:51 +0200
                Re: RE Module Performance Chris Angelico <rosuav@gmail.com> - 2013-07-29 00:07 +0100
                Re: RE Module Performance Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-07-26 22:38 +0200
        Re: RE Module Performance Devyn Collier Johnson <devyncjohnson@gmail.com> - 2013-07-25 09:44 -0400
        Re: RE Module Performance Ian Kelly <ian.g.kelly@gmail.com> - 2013-07-25 15:53 -0500
    Re: RE Module Performance MRAB <python@mrabarnett.plus.com> - 2013-07-13 00:16 +0100
    Re: RE Module Performance Tim Delaney <timothy.c.delaney@gmail.com> - 2013-07-14 05:34 +1000
    Re: RE Module Performance Devyn Collier Johnson <devyncjohnson@gmail.com> - 2013-07-16 06:30 -0400
      Re: RE Module Performance 88888 Dihedral <dihedral88888@gmail.com> - 2013-07-18 13:17 -0700

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