Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!aioe.org!.POSTED!not-for-mail
From: Mel <mwilson@the-wire.com>
Newsgroups: comp.lang.python
Subject: Re: Why do directly imported variables behave differently than those attached to imported module?
Followup-To: comp.lang.python
Date: Tue, 03 May 2011 13:00:28 -0400
Organization: Aioe.org NNTP Server
Lines: 44
Message-ID: <ippcba$qt0$1@speranza.aioe.org>
References: <d8d1d20e-2edd-49e5-917c-f338ef35006f@l18g2000yql.googlegroups.com>
Reply-To: mwilson@the-wire.com
NNTP-Posting-Host: Ako0BITcBw0jkGmD9p7rgQ.user.speranza.aioe.org
Mime-Version: 1.0
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 7Bit
X-Complaints-To: abuse@aioe.org
User-Agent: KNode/4.4.8
X-Notice: Filtered by postfilter v. 0.8.2
Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:4556

Dun Peal wrote:

> Hi!
> 
> Here's the demonstrating code:
> 
>     # module foo.py
>     var = 0
> 
>     def set():
>         global var
>         var = 1
> 
> Script using this module:
> 
>     import foo
>     from foo import *
> 
>     print var, foo.var
>     set()
>     print var, foo.var
> 
> Script output:
> 
>     0 0
>     0 1
> 
> Apparently, the `var` we imported from `foo` never got set, but
> `foo.var` on the imported `foo` - did. Why?

They're different because -- they're different.  `foo.var` is defined in the 
namespace of the foo module.  Introspectively, you would access it as 
`foo.__dict__['var']` .

Plain `var` is in your script's namespace so you could access it as 
`globals()['var']` .  The values given to the vars are immutable integers, 
so assignment works by rebinding.  The two different bindings in 
foo.__dict__ and globals() get bound to different integer objects.

Note too the possible use of `globals()['foo'].__dict__['var'] .  (Hope 
there are no typos in this post.)

	Mel.