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Re: Importing variables non-deterministic?

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Op 19-08-13 11:18, Chris Angelico schreef:
> On Mon, Aug 19, 2013 at 10:03 AM, Antoon Pardon
> <antoon.pardon@rece.vub.ac.be> wrote:
>> This is irrelevant. That some context defines a constant, and that you
>> can use a variable with the same name as a constant in python, doesn't
>> contradict the statement that python (as a language) doesn't has
>> constants. There is nothing in the language that would prevent buggy
>> code from changing any of those variables. So from a python point of
>> views these are just global variables. Just as the struct_global.y was
>> in the original contribution.
> 
> And there's nothing preventing a program from using ctypes to
> overwrite an object's refcount, thus causing a segfault. So?

Yes so? What is your point? Since Cpython caches small integers
there is probably nothing preventing a program from using ctypes
to make the number three behave as the number five. That doesn't
mean that the language define three and five to be equal.

A language having constants, does mean that the language can prevent
a name from being reassigned.

> The issue
> was regarding imports, and it's perfectly safe to import a constant,
> even if the interpreter doesn't protect you from then being a total
> idiot and changing it.

Python doesn't have constants, so you statement about importing a
constant doesn't make sense. The point is that python doesn't provide
the mechanism for protecting names against reassignments. So you
don't know whether the variable you think of as a constant is so
in reality. And this from a pure language definition point of view.
That you can use tools that make the interpreter no longer behave
as the language should, doesn't negate that.

-- 
Antoon Pardon.

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Thread

Importing variables non-deterministic? tmellman@googlemail.com - 2013-08-17 07:25 -0700
  Re: Importing variables non-deterministic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-08-17 15:01 +0000
    Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 09:14 +0200
    Re: Importing variables non-deterministic? Dave Angel <davea@davea.name> - 2013-08-19 07:45 +0000
    Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 10:16 +0200
      Re: Importing variables non-deterministic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-08-19 16:57 +0000
        Re: Importing variables non-deterministic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-08-19 17:16 +0000
          Re: Importing variables non-deterministic? Chris Angelico <rosuav@gmail.com> - 2013-08-19 18:25 +0100
        Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 19:40 +0200
    Re: Importing variables non-deterministic? Chris Angelico <rosuav@gmail.com> - 2013-08-19 09:32 +0100
      Re: Importing variables non-deterministic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-08-19 17:05 +0000
        Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 22:34 +0200
          Re: Importing variables non-deterministic? Steven D'Aprano <steve@pearwood.info> - 2013-08-20 05:48 +0000
            Re: Importing variables non-deterministic? wxjmfauth@gmail.com - 2013-08-19 23:40 -0700
            Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-20 08:55 +0200
              Re: Importing variables non-deterministic? wxjmfauth@gmail.com - 2013-08-20 00:31 -0700
                Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-20 09:55 +0200
                Re: Importing variables non-deterministic? wxjmfauth@gmail.com - 2013-08-20 02:15 -0700
    Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 11:03 +0200
    Re: Importing variables non-deterministic? Chris Angelico <rosuav@gmail.com> - 2013-08-19 10:18 +0100
    Re: Importing variables non-deterministic? Peter Otten <__peter__@web.de> - 2013-08-19 11:49 +0200
    Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 13:54 +0200
    Re: Importing variables non-deterministic? Dave Angel <davea@davea.name> - 2013-08-19 12:33 +0000
    Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 16:55 +0200
    Re: Importing variables non-deterministic? Chris Angelico <rosuav@gmail.com> - 2013-08-19 16:04 +0100
    Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 19:25 +0200
    Re: Importing variables non-deterministic? Ben Finney <ben+python@benfinney.id.au> - 2013-08-20 11:14 +1000

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