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Date: Thu, 16 Jan 2014 19:01:51 +0100
Subject: Re: Guessing the encoding from a BOM
From: =?ISO-8859-1?Q?Bj=F6rn_Lindqvist?= <bjourne@gmail.com>
To: "Steven D'Aprano" <steve+comp.lang.python@pearwood.info>
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Xref: csiph.com comp.lang.python:64093

2014/1/16 Steven D'Aprano <steve+comp.lang.python@pearwood.info>:
> def guess_encoding_from_bom(filename, default):
>     with open(filename, 'rb') as f:
>         sig =3D f.read(4)
>     if sig.startswith((b'\xFE\xFF', b'\xFF\xFE')):
>         return 'utf_16'
>     elif sig.startswith((b'\x00\x00\xFE\xFF', b'\xFF\xFE\x00\x00')):
>         return 'utf_32'
>     else:
>         return default

You might want to add the utf8 bom too: '\xEF\xBB\xBF'.

>     (4) Don't return anything, but raise an exception. (But
>         which exception?)

I like this option the most because it is the most "fail fast". If you
return 'undefined' the error might happen hours later or not at all in
some cases.


--=20
mvh/best regards Bj=F6rn Lindqvist