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From: Ian Kelly <ian.g.kelly@gmail.com>
Date: Tue, 31 May 2011 15:47:33 -0600
Subject: Re: Something is rotten in Denmark...
To: Martin Manns <mmanns@gmx.net>
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On Tue, May 31, 2011 at 3:14 PM, Martin Manns <mmanns@gmx.net> wrote:
> $ python
> Python 2.6.6 (r266:84292, Apr 20 2011, 11:58:30)
> [GCC 4.5.2] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
>>>> fs=[]
>>>> fs = [(lambda n: i + n) for i in range(10)]
>>>> [fs[i](1) for i in range(10)]
> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

This works by accident.

>>> [fs[i](1) for i in range(10)]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>>> [fs[0](1) for i in range(10)]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>>> [f(1) for f in fs]
[10, 10, 10, 10, 10, 10, 10, 10, 10, 10]

The i variable is part of the global scope, and as you iterate over
range(10) again it coincidentally takes on the same values as in the
original list comprehension.  You don't see this in Python 3 because
the scope of i is limited to the list comprehension, not global.

Cheers,
Ian