Groups > comp.lang.python > #20131

Re: frozendict

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Date	2012-02-09 21:30 -0500
Subject	Re: frozendict
From	Nathan Rice <nathan.alexander.rice@gmail.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.5630.1328841051.27778.python-list@python.org> (permalink)

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On Thu, Feb 9, 2012 at 8:24 PM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> On Thu, 09 Feb 2012 09:35:52 -0700, Ian Kelly wrote:
>
>> On Thu, Feb 9, 2012 at 8:19 AM, Nathan Rice
>> <nathan.alexander.rice@gmail.com> wrote:
>>> As I said, two dictionaries created from the same input will be the
>>> same...
>>
>> That's an implementation detail, not a guarantee.  It will hold for
>> current versions of CPython but not necessarily for other Python
>> implementations.
>
> That day may be sooner than you think. It is very likely that in Python
> 3.3, dict order will be randomized on creation as a side-effect of adding
> a random salt to hashes to prevent a serious vulnerability in dicts.
>
> http://securitytracker.com/id/1026478
>
> http://bugs.python.org/issue13703
>
>
> If there is anyone still assuming that dicts have a predictable order,
> they're going to be in for a nasty surprise one of these days.

The only thing needed to avoid the hash collision is that your hash
function is not not 100% predictable just by looking at the python
source code.  I don't see why every dict would have to be created
differently.  I would think having the most ubiquitous data structure
in your language be more predictable would be a priority.  Oh well....


Nathan

Thread

Re: frozendict Nathan Rice <nathan.alexander.rice@gmail.com> - 2012-02-08 22:43 -0500
  Re: frozendict Duncan Booth <duncan.booth@invalid.invalid> - 2012-02-09 10:33 +0000
    Re: frozendict Nathan Rice <nathan.alexander.rice@gmail.com> - 2012-02-09 09:36 -0500
      Re: frozendict Duncan Booth <duncan.booth@invalid.invalid> - 2012-02-09 14:52 +0000
        Re: frozendict Nathan Rice <nathan.alexander.rice@gmail.com> - 2012-02-09 10:19 -0500
          Re: frozendict Duncan Booth <duncan.booth@invalid.invalid> - 2012-02-09 18:47 +0000
        Re: frozendict Ian Kelly <ian.g.kelly@gmail.com> - 2012-02-09 09:35 -0700
          Re: frozendict Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-02-10 01:24 +0000
            Re: frozendict Nathan Rice <nathan.alexander.rice@gmail.com> - 2012-02-09 21:30 -0500
            Re: frozendict Terry Reedy <tjreedy@udel.edu> - 2012-02-09 22:33 -0500
            Re: frozendict Chris Angelico <rosuav@gmail.com> - 2012-02-10 21:08 +1100
            Re: frozendict Nathan Rice <nathan.alexander.rice@gmail.com> - 2012-02-10 11:53 -0500
            Re: frozendict Chris Rebert <clp2@rebertia.com> - 2012-02-10 09:00 -0800
            Re: frozendict Nathan Rice <nathan.alexander.rice@gmail.com> - 2012-02-10 13:14 -0500
              Re: frozendict John Nagle <nagle@animats.com> - 2012-02-10 10:57 -0800
                Re: frozendict 88888 Dihedral <dihedral88888@googlemail.com> - 2012-02-10 21:52 -0800
                Re: frozendict John Nagle <nagle@animats.com> - 2012-02-13 13:15 -0800
        Re: frozendict Nathan Rice <nathan.alexander.rice@gmail.com> - 2012-02-09 11:50 -0500

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