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Groups > comp.lang.python > #67277

Re: Tuples and immutability

References <lennh4$kpm$1@cabale.usenet-fr.net> <059a3d10-453a-40fd-99f9-33ceb8ecabf7@googlegroups.com>
Date 2014-03-01 12:39 +1100
Subject Re: Tuples and immutability
From Chris Angelico <rosuav@gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.7491.1393637948.18130.python-list@python.org> (permalink)

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On Sat, Mar 1, 2014 at 11:22 AM, Mark H. Harris <harrismh777@gmail.com> wrote:
> lists within a tuple should be converted to tuples.    If you want a tuple to hold a list,  make it a list in the first place.  Tuples should not be changed... and as you point out... half changing a tuple is not a good condition if there is an exception...
>

A tuple is perfectly fine containing a list. If you want a tuple to be
"recursively immutable", then you're talking about hashability, and
*then* yes, you need to convert everything into tuples - but a tuple
is not just an immutable list. The two are quite different in pupose.

> I really think this is a bug; honestly.  IMHO it should be an error to use  +=  with an immutable type and that means not at all.  In other words,  the list should not even be considered, because we're talking about changing a tuple... which should not be changed (nor should its members be changed).
>

Definitely not! Incrementing an integer with += is a perfectly normal
thing to do:

x = 5
x += 1

It's just a matter of knowing the language and understanding what's going on.

ChrisA

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Thread

Tuples and immutability Eric Jacoboni <eric.jacoboni@gmail.com> - 2014-02-27 17:01 +0100
  Re: Tuples and immutability Zachary Ware <zachary.ware+pylist@gmail.com> - 2014-02-27 10:13 -0600
    Re: Tuples and immutability Eric Jacoboni <eric.jacoboni@gmail.com> - 2014-02-27 17:27 +0100
      Re: Tuples and immutability Chris Angelico <rosuav@gmail.com> - 2014-02-28 03:33 +1100
      Re: Tuples and immutability Zachary Ware <zachary.ware+pylist@gmail.com> - 2014-02-27 10:47 -0600
      Re: Tuples and immutability Nick Timkovich <prometheus235@gmail.com> - 2014-02-27 15:47 -0600
      Re: Tuples and immutability Chris Angelico <rosuav@gmail.com> - 2014-02-28 08:52 +1100
      Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-27 15:18 -0700
      Re: Tuples and immutability Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2014-03-01 18:55 +0000
  Re: Tuples and immutability Chris Angelico <rosuav@gmail.com> - 2014-02-28 03:14 +1100
  Re: Tuples and immutability Marko Rauhamaa <marko@pacujo.net> - 2014-02-27 18:19 +0200
    Re: Tuples and immutability John O'Hagan <research@johnohagan.com> - 2014-02-28 16:17 +1100
      Re: Tuples and immutability Marko Rauhamaa <marko@pacujo.net> - 2014-02-28 09:54 +0200
  Re: Tuples and immutability Joshua Landau <joshua@landau.ws> - 2014-02-28 14:41 +0000
  Re: Tuples and immutability Chris Angelico <rosuav@gmail.com> - 2014-03-01 01:43 +1100
  Re: Tuples and immutability "Mark H. Harris" <harrismh777@gmail.com> - 2014-02-28 16:22 -0800
    Re: Tuples and immutability Eric Jacoboni <eric.jacoboni@gmail.com> - 2014-03-01 02:27 +0100
      Re: Tuples and immutability "Mark H. Harris" <harrismh777@gmail.com> - 2014-02-28 20:45 -0800
        Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-28 22:34 -0700
          Re: Tuples and immutability "Mark H. Harris" <harrismh777@gmail.com> - 2014-02-28 21:50 -0800
            Re: Tuples and immutability Ned Batchelder <ned@nedbatchelder.com> - 2014-03-01 12:56 -0500
      Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-28 22:26 -0700
    Re: Tuples and immutability Chris Angelico <rosuav@gmail.com> - 2014-03-01 12:39 +1100
    Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-28 22:16 -0700
      Re: Tuples and immutability "Mark H. Harris" <harrismh777@gmail.com> - 2014-02-28 22:16 -0800
        Re: Tuples and immutability Chris Angelico <rosuav@gmail.com> - 2014-03-01 17:29 +1100
        Re: Tuples and immutability Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-03-01 14:54 +0000
          Re: Tuples and immutability "Mark H. Harris" <harrismh777@gmail.com> - 2014-03-01 13:01 -0800
      Re: Tuples and immutability "Mark H. Harris" <harrismh777@gmail.com> - 2014-02-28 22:25 -0800
        Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-01 12:45 -0700
      Re: Tuples and immutability "Mark H. Harris" <harrismh777@gmail.com> - 2014-03-01 13:21 -0800
        Re: Tuples and immutability Eric Jacoboni <eric.jacoboni@gmail.com> - 2014-03-02 03:04 +0100
          Re: Tuples and immutability "Mark H. Harris" <harrismh777@gmail.com> - 2014-03-01 18:28 -0800
          Re: Tuples and immutability Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-02 05:32 -0700
            Re: Tuples and immutability Eric Jacoboni <eric.jacoboni@gmail.com> - 2014-03-02 14:38 +0100
              Re: Tuples and immutability Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-03-02 14:05 +0000
                Re: Tuples and immutability Eric Jacoboni <eric.jacoboni@gmail.com> - 2014-03-02 15:17 +0100
                Re: Tuples and immutability "albert visser" <albert.visser@gmail.com> - 2014-03-02 15:37 +0100
        Re: Tuples and immutability "Mark H. Harris" <harrismh777@gmail.com> - 2014-03-01 18:15 -0800

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