[Patches] [ python-Patches-1180995 ] binary formats for marshalling floats

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Patches item #1180995, was opened at 2005-04-11 20:50
Message generated for change (Comment added) made by mwh
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Category: Core (C code)
Group: Python 2.5
Status: Open
Resolution: None
Priority: 5
Submitted By: Michael Hudson (mwh)
Assigned to: Nobody/Anonymous (nobody)
Summary: binary formats for marshalling floats

Initial Comment:
This patch makes marshal.c use a binary format for floats when 
version > 1 using _PyFloat_Pack8, _PyFloat_Unpack8 (as 
suggested on python-dev).

It doesn't actually update the default version yet, so you have to be 
explicit about it:

>>> marshal.dumps(1.0, 2) 
'g\x00\x00\x00\x00\x00\x00\xf0?'

This almost certainly falls in the realm of platform-depedent accident 
-- what does frexp do with special values? -- but on my system:

>>> inf = 1e308*1e308
>>> inf
inf
>>> marshal.dumps(inf, 2)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
ValueError: unmarshallable object



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>Comment By: Michael Hudson (mwh)
Date: 2005-04-14 08:53

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New patch.  Main difference is updating MAGIC.

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Comment By: Michael Hudson (mwh)
Date: 2005-04-12 18:24

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New patch.  This attacks error handling in unmarshalling code objects to 
be more likely to reflect the real reason unmarshalling fails, and updates 
the default marshal version to 2.

Combined with my float packing changes this gives us a much more 
coherent float marshalling/unmarshalling story.

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Comment By: Tim Peters (tim_one)
Date: 2005-04-11 21:10

Message:
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Yes, C89 says nothing about what frexp() does in the 
presence of infinities, NaNs or signed zeroes.  That's why 
whether pickling/unpickling (proto >= 1), or struct 
packing/unpacking (std mode), such things appears to work-- 
or how it fails --have always been platform-dependent 
accidents,

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