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Groups > comp.lang.python > #92387

Re: enhancement request: make py3 read/write py2 pickle format

References (2 earlier) <CABicbJ+e02OKYi48kbjFFutyLUGgkEQdiPZqiB657AO+QKu11Q@mail.gmail.com> <mailman.325.1433891190.13271.python-list@python.org> <55778208$0$2899$e4fe514c@news2.news.xs4all.nl> <mailman.328.1433897321.13271.python-list@python.org> <5577b46d$0$12975$c3e8da3$5496439d@news.astraweb.com>
From Devin Jeanpierre <jeanpierreda@gmail.com>
Date 2015-06-09 21:48 -0700
Subject Re: enhancement request: make py3 read/write py2 pickle format
Newsgroups comp.lang.python
Message-ID <mailman.332.1433911768.13271.python-list@python.org> (permalink)

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On Tue, Jun 9, 2015 at 8:52 PM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> On Wednesday 10 June 2015 10:47, Devin Jeanpierre wrote:
>
>> Passing around data that can be put into ast.literal_eval is
>> synonymous with passing around data taht can be put into eval. It
>> sounds like a trap.
>
> In what way?

I misspoke, and instead of "synonymous", meant "also means".
(Implication, not equivalence.)

>> For human readable serialized data, text format protocol buffers are
>> seriously underrated. (Relatedly: underdocumented, too.)
>
> Ironically, literal_eval is designed to process text-format protocols using
> human-readable Python syntax for common data types like int, str, and dict.

"Protocol buffers" are a specific technology, not an abstract concept,
and literal_eval is not a great idea.

* the common serializer (repr) does not output a canonical form, and
  can serialize things in a way that they can't be deserialized
* there is no schema
* there is no well understood migration story for when the data you
  load and store changes
* it is not usable from other programming languages
* it encourages the use of eval when literal_eval becomes inconvenient
  or insufficient
* It is not particularly well specified or documented compared to the
  alternatives.
* The types you get back differ in python 2 vs 3

For most apps, the alternatives are better. Irmen's serpent library is
strictly better on every front, for example. (Except potentially
security, who knows.)

At least it's better than pickle, security wise. Reliability wise,
repr is a black hole, so no dice. :(

-- Devin

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Re: enhancement request: make py3 read/write py2 pickle format Chris Angelico <rosuav@gmail.com> - 2015-06-10 09:06 +1000
  Re: enhancement request: make py3 read/write py2 pickle format Irmen de Jong <irmen.NOSPAM@xs4all.nl> - 2015-06-10 02:17 +0200
    Re: enhancement request: make py3 read/write py2 pickle format Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-06-09 17:47 -0700
      Re: enhancement request: make py3 read/write py2 pickle format Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-06-10 13:52 +1000
        Re: enhancement request: make py3 read/write py2 pickle format random832@fastmail.us - 2015-06-09 23:57 -0400
          Re: enhancement request: make py3 read/write py2 pickle format Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-06-10 15:43 +1000
        Re: enhancement request: make py3 read/write py2 pickle format Chris Angelico <rosuav@gmail.com> - 2015-06-10 14:00 +1000
        Re: enhancement request: make py3 read/write py2 pickle format Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-06-09 21:48 -0700
          Re: enhancement request: make py3 read/write py2 pickle format Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-06-10 19:36 +1000
            Re: enhancement request: make py3 read/write py2 pickle format Irmen de Jong <irmen.NOSPAM@xs4all.nl> - 2015-06-10 19:34 +0200
            Re: enhancement request: make py3 read/write py2 pickle format Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-06-10 15:10 -0700
              Re: enhancement request: make py3 read/write py2 pickle format Steven D'Aprano <steve@pearwood.info> - 2015-06-11 13:21 +1000
                Re: enhancement request: make py3 read/write py2 pickle format Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-06-10 22:39 -0700
                Re: enhancement request: make py3 read/write py2 pickle format Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-06-11 19:20 +1000
            Re: enhancement request: make py3 read/write py2 pickle format Terry Reedy <tjreedy@udel.edu> - 2015-06-10 19:25 -0400
            Re: enhancement request: make py3 read/write py2 pickle format Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-06-10 16:39 -0700
            Re: enhancement request: make py3 read/write py2 pickle format Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-06-10 16:48 -0700
            Re: enhancement request: make py3 read/write py2 pickle format Terry Reedy <tjreedy@udel.edu> - 2015-06-10 19:46 -0400
            Re: enhancement request: make py3 read/write py2 pickle format Chris Angelico <rosuav@gmail.com> - 2015-06-11 09:58 +1000
            Re: enhancement request: make py3 read/write py2 pickle format Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-06-10 17:02 -0700
              Re: enhancement request: make py3 read/write py2 pickle format Marko Rauhamaa <marko@pacujo.net> - 2015-06-11 07:08 +0300
            Re: enhancement request: make py3 read/write py2 pickle format Serhiy Storchaka <storchaka@gmail.com> - 2015-06-11 14:11 +0300
    Re: enhancement request: make py3 read/write py2 pickle format Chris Angelico <rosuav@gmail.com> - 2015-06-10 11:03 +1000

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