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Re: Generating valid identifiers

Date 2012-07-26 20:08 +0200
From Laszlo Nagy <gandalf@shopzeus.com>
Subject Re: Generating valid identifiers
References <mailman.2604.1343305588.4697.python-list@python.org> <50116281$0$29978$c3e8da3$5496439d@news.astraweb.com>
Newsgroups comp.lang.python
Message-ID <mailman.2621.1343326154.4697.python-list@python.org> (permalink)

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>> * Would it be a problem to use CRC32 instead of SHA? (Since security is
>> not a problem, and CRC32 is faster.)
> What happens if you get a collision?
>
> That is, you have two different long identifiers:
>
> a.b.c.d...something
> a.b.c.d...anotherthing
>
> which by bad luck both hash to the same value:
>
> a.b.c.d.$AABB99
> a.b.c.d.$AABB99
>
> (or whatever).
Yes, that was the question. How do I avoid that? (Of course I can avoid 
that by using a full sha256 hash value.)
>> * Can somebody think of a
>> better algorithm, that would give a bigger chance of recognizing the
>> original identifier from the modified one?
> Rather than truncating the most significant part of the identifier, the
> field name, you should truncate the least important part, the middle.
>
> a.b.c.d.e.f.g.something
>
> goes to:
>
> a.b...g.something
>
> or similar.
Yes, this is a good idea. Thank you.

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Thread

Generating valid identifiers Laszlo Nagy <gandalf@shopzeus.com> - 2012-07-26 14:26 +0200
  Re: Generating valid identifiers Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-26 15:30 +0000
    Re: Generating valid identifiers Laszlo Nagy <gandalf@shopzeus.com> - 2012-07-26 20:08 +0200
    Re: Generating valid identifiers Ian Kelly <ian.g.kelly@gmail.com> - 2012-07-26 13:28 -0600
      Re: Generating valid identifiers Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-27 01:54 +0000
        Re: Generating valid identifiers Laszlo Nagy <gandalf@shopzeus.com> - 2012-07-27 09:34 +0200
    Re: Generating valid identifiers Ian Kelly <ian.g.kelly@gmail.com> - 2012-07-26 14:00 -0600
    Re: Generating valid identifiers Laszlo Nagy <gandalf@shopzeus.com> - 2012-07-27 09:28 +0200
    Re: Generating valid identifiers Laszlo Nagy <gandalf@shopzeus.com> - 2012-07-27 11:59 +0200

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