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From: Ian Kelly <ian.g.kelly@gmail.com>
Date: Wed, 25 May 2011 14:54:25 -0600
Subject: Re: Python 3.2 bug? Reading the last line of a file
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On Wed, May 25, 2011 at 2:00 PM, MRAB <python@mrabarnett.plus.com> wrote:
> You're opening the file in text mode, and seeking relative to the end
> of the file is not allowed in text mode, presumably because the file
> contents have to be decoded, and, in general, seeking to an arbitrary
> position within a sequence of encoded bytes can have undefined results
> when you attempt to decode to Unicode starting from that position.
>
> The strange thing is that you _are_ allowed to seek relative to the
> start of the file.

I think that with text files seek() is only really meant to be called
with values returned from tell(), which may include the decoder state
in its return value.