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To: python-list@python.org
From: Ben Finney <ben+python@benfinney.id.au>
Subject: Re: Terminology: =?utf-8?B?4oCccmVmZXJlbmNl4oCd?= versus =?utf-8?B?4oCccG9pbnRlcuKAnQ==?=
Date: Sat, 12 Sep 2015 14:52:51 +1000
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Random832 <random832@fastmail.com> writes:

> Ben Finney <ben+python@benfinney.id.au> writes:
> > With the significant difference that “pointer” implies that it has its
> > own value accessible directly by the running program, such as a pointer
> > in C.
>
> Its own value *is* what you're accessing when you assign or return it.

You're not describing Python references. But I don't know what you are
describing with all those “it”s — what language, what behaviour, what
concept?

Can you clarify what you mean, and what in my description you are
disagreeing with?

> > That's different from a “reference”, which to my understanding
> > implies the running program does *not* normally have direct access
> > to it as a distinct value. The only way you can use a reference is
> > to get at the object to which it refers.
>
> In C++, references cannot be reassigned. I consider *that* the
> fundamental difference - a pointer is a variable that you can reassign
> and return; a reference always refers to the same object once created.

Sure, that will work fine.

So in Python, we don't have pointers because we don't have access to
change or reassign them.

A Python reference isn't accessible and can't be changed; you can just
make another reference and switch to that.

You can't, for example, keep the old reference (there are no references
to references in Python), because they're not accessible as values in
themselves. Once you assign a different reference, the old one is gone
and can't be found again.

-- 
 \            “[T]he great menace to progress is not ignorance but the |
  `\           illusion of knowledge.” —Daniel J. Boorstin, historian, |
_o__)                                                        1914–2004 |
Ben Finney