[ python-Bugs-1473625 ] cPickle produces locale-dependent dumps

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Bugs item #1473625, was opened at 2006-04-20 17:25
Message generated for change (Comment added) made by ivilata
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Category: Python Library
Group: Python 2.5
Status: Open
Resolution: None
Priority: 5
Submitted By: Ivan Vilata i Balaguer (ivilata)
Assigned to: Nobody/Anonymous (nobody)
Summary: cPickle produces locale-dependent dumps

Initial Comment:
Dumping a float with cPickle produces a result which is
locale-dependent.  This causes problems when trying to
load the dump under a different locale (the regular
pickle module is not affected by this bug).  IMHO, the
dump should be locale-independent to ensure
portability. See the attached file for a sample session
log showing the behaviour of both pickle and cPickle
under C and ca_ES.UTF-8 locales (Catalan uses a comma
to separate the integer and decimal part).


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>Comment By: Ivan Vilata i Balaguer (ivilata)
Date: 2006-04-21 11:42

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The problem seems to be in save_float() in the cPickle.c
module.  It uses PyOS_snprintf() to dump floats, but it is
locale-dependent.  Fortunately, the PyOS_ascii_formatd()
function can be used.  The attached patch seems to fix the
problem, and pickling tests run OK.  It would be nice to see
this patch applied to 2.4 also.

(BTW, I meant PEP 331 in the previous comment, not 311, sorry.)

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Comment By: Martin v. Löwis (loewis)
Date: 2006-04-20 23:54

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Right, cPickle should use C locale floating point numbers,
using the PEP 331 API. Would you like to investigate a patch?

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Comment By: Ivan Vilata i Balaguer (ivilata)
Date: 2006-04-20 17:28

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As a side note, does this have anything to do with PEP 311?
 http://www.python.org/dev/peps/pep-0331/

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