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Groups > comp.lang.python > #32465

Re: Negative array indicies and slice()

Date 2012-10-29 23:53 -0600
From Michael Torrie <torriem@gmail.com>
Subject Re: Negative array indicies and slice()
References (6 earlier) <508E1BC9.3000308@r3dsolutions.com> <CALwzid=rhea2aMXM_St2FwTiAx+cnZ20_H6RtwW0_81uSQAFBQ@mail.gmail.com> <mailman.3053.1351550917.27098.python-list@python.org> <508f1910$0$29967$c3e8da3$5496439d@news.astraweb.com> <508EDA40.8020003@r3dsolutions.com>
Newsgroups comp.lang.python
Message-ID <mailman.3072.1351576425.27098.python-list@python.org> (permalink)

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On 10/29/2012 01:34 PM, Andrew Robinson wrote:
> No, I don't think it big and complicated.  I do think it has timing 
> implications which are undesirable because of how *much* slices are used.
> In an embedded target -- I have to optimize; and I will have to reject 
> certain parts of Python to make it fit and run fast enough to be useful.

Since you can't port the full Python system to your embedded machine
anyway, why not just port a subset of python and modify it to suit your
needs right there in the C code.  It would be a fork, yes, but any port
to this target will be a fork anyway.  No matter how you cut it, it
won't be easy at all, and won't be easy to maintain.  You'll basically
be writing your own implementation of Python (that's what
python-on-a-chip is, and that's why it's closer to Python 2.x than
Python 3).  That's totally fine, though.  I get the impression you think
you will be able to port cPython as is to your target.  Without a libc,
an MMU on the CPU, and a kernel, it's not going to just compile and run.

Anyway, the only solution, given your constraints, is to implement your
own python interpreter to handle a subset of Python, and modify it to
suit your tastes.  What you want with slicing behavior changes has no
place in the normal cPython implementation, for a lot of reasons.  The
main one is that it is already possible to implement what you are
talking about in your own python class, which is a fine solution for a
normal computer with memory and CPU power available.

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Negative array indicies and slice() andrewr3mail@gmail.com - 2012-10-28 20:12 -0700
  Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-28 21:42 -0600
    Re: Negative array indicies and slice() andrewr3mail@gmail.com - 2012-10-28 21:00 -0700
      Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-28 22:25 -0600
        Re: Negative array indicies and slice() Andrew <andrewr3mail@gmail.com> - 2012-10-29 00:54 -0700
          Re: Negative array indicies and slice() Chris Rebert <clp2@rebertia.com> - 2012-10-29 01:18 -0700
          Re: Negative array indicies and slice() Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-29 11:19 +0000
            Re: Negative array indicies and slice() Chris Angelico <rosuav@gmail.com> - 2012-10-29 22:32 +1100
            Re: Negative array indicies and slice() Andrew Robinson <andrew3@r3dsolutions.com> - 2012-10-28 21:52 -0700
            Re: Negative array indicies and slice() Chris Angelico <rosuav@gmail.com> - 2012-10-29 23:40 +1100
              Re: Negative array indicies and slice() Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-29 22:02 +0000
            Re: Negative array indicies and slice() Andrew Robinson <andrew3@r3dsolutions.com> - 2012-10-28 23:01 -0700
              Re: Negative array indicies and slice() Roy Smith <roy@panix.com> - 2012-10-29 09:52 -0400
                Re: Negative array indicies and slice() Andrew Robinson <andrew3@r3dsolutions.com> - 2012-10-29 08:20 -0700
                Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-29 17:01 -0600
                Re: Negative array indicies and slice() Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2012-10-30 00:04 +0000
                Re: Negative array indicies and slice() Andrew Robinson <andrew3@r3dsolutions.com> - 2012-10-29 16:54 -0700
                Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-30 02:15 -0600
            Re: Negative array indicies and slice() Chris Angelico <rosuav@gmail.com> - 2012-10-30 00:53 +1100
            Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-29 11:09 -0600
            Re: Negative array indicies and slice() Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-29 22:14 +0000
            Re: Negative array indicies and slice() Andrew Robinson <andrew3@r3dsolutions.com> - 2012-10-29 08:42 -0700
              Re: Negative array indicies and slice() Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-30 00:02 +0000
                Re: Negative array indicies and slice() Andrew Robinson <andrew3@r3dsolutions.com> - 2012-10-29 12:34 -0700
                Re: Negative array indicies and slice() Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-30 08:17 +0000
                Re: Negative array indicies and slice() Andrew Robinson <andrew3@r3dsolutions.com> - 2012-10-30 08:47 -0700
                Re: Negative array indicies and slice() Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-10-30 23:48 +0000
                Re: Negative array indicies and slice() Michael Torrie <torriem@gmail.com> - 2012-10-30 23:29 -0600
                Re: Negative array indicies and slice() Michael Torrie <torriem@gmail.com> - 2012-10-29 23:53 -0600
                Re: Negative array indicies and slice() Andrew Robinson <andrew3@r3dsolutions.com> - 2012-10-29 17:04 -0700
            Re: Negative array indicies and slice() Chris Angelico <rosuav@gmail.com> - 2012-10-30 09:55 +1100
            Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-29 17:07 -0600
              Re: Negative array indicies and slice() Roy Smith <roy@panix.com> - 2012-10-29 19:24 -0400
                Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-29 17:43 -0600
                Re: Negative array indicies and slice() Roy Smith <roy@panix.com> - 2012-10-29 20:17 -0400
                Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-29 18:05 -0600
            Re: Negative array indicies and slice() Andrew Robinson <andrew3@r3dsolutions.com> - 2012-10-29 11:00 -0700
            Re: Negative array indicies and slice() Chris Kaynor <ckaynor@zindagigames.com> - 2012-10-29 18:49 -0700
            Re: Negative array indicies and slice() Andrew Robinson <andrew3@r3dsolutions.com> - 2012-10-29 15:39 -0700
            Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-29 23:55 -0600
            Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-30 00:51 -0600
            Re: Negative array indicies and slice() Andrew Robinson <andrew3@r3dsolutions.com> - 2012-10-29 17:17 -0700
            Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-30 01:21 -0600
            Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-30 01:32 -0600
            Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-30 02:46 -0600
            Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-30 12:02 -0600
            Re: Negative array indicies and slice() Andrew Robinson <andrew3@r3dsolutions.com> - 2012-10-30 07:21 -0700
            Re: Negative array indicies and slice() Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-10-30 21:33 +0000
              Re: Negative array indicies and slice() Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-31 10:07 +0000
                Re: Negative array indicies and slice() Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-10-31 16:01 +0000
            Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-30 15:47 -0600
            Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-30 15:55 -0600
            Re: Negative array indicies and slice() Chris Angelico <rosuav@gmail.com> - 2012-10-31 09:00 +1100
            Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-30 16:02 -0600
            Re: Negative array indicies and slice() Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-10-30 23:30 +0000
          Re: Negative array indicies and slice() Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-29 11:27 -0600
          Re: Negative array indicies and slice() Andrew Robinson <andrew3@r3dsolutions.com> - 2012-10-29 16:33 -0700
        Re: Negative array indicies and slice() Andrew <andrewr3mail@gmail.com> - 2012-10-29 00:54 -0700
    Re: Negative array indicies and slice() andrewr3mail@gmail.com - 2012-10-28 21:00 -0700
    Re: Negative array indicies and slice() Andrew <andrewr3mail@gmail.com> - 2012-10-28 21:09 -0700
      Re: Negative array indicies and slice() alex23 <wuwei23@gmail.com> - 2012-10-28 21:44 -0700
        Re: Negative array indicies and slice() andrewr3mail@gmail.com - 2012-10-29 01:24 -0700
          Re: Negative array indicies and slice() Chris Rebert <clp2@rebertia.com> - 2012-10-29 01:37 -0700
            Re: Negative array indicies and slice() andrewr3mail@gmail.com - 2012-10-29 01:59 -0700
              Re: Negative array indicies and slice() Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-10-29 09:36 +0000
              Re: Negative array indicies and slice() Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-29 10:34 +0000
            Re: Negative array indicies and slice() andrewr3mail@gmail.com - 2012-10-29 01:59 -0700
      Re: Negative array indicies and slice() Paul Rubin <no.email@nospam.invalid> - 2012-10-28 22:14 -0700
        Re: Negative array indicies and slice() andrewr3mail@gmail.com - 2012-10-29 01:08 -0700
          Re: Negative array indicies and slice() Chris Rebert <clp2@rebertia.com> - 2012-10-29 01:26 -0700
    Re: Negative array indicies and slice() Andrew <andrewr3mail@gmail.com> - 2012-10-28 21:09 -0700
  Re: Negative array indicies and slice() MRAB <python@mrabarnett.plus.com> - 2012-10-29 03:45 +0000
  Re: Negative array indicies and slice() 88888 Dihedral <dihedral88888@googlemail.com> - 2012-11-01 18:08 -0700

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