A fix for OverflowError in 64bits platforms
Manuel Vazquez Acosta
mva.led at gmail.com
Thu Jul 3 10:20:54 EDT 2008
Hi all,
I'm debugging a Plone site in an AMD64 laptop. When I first tried to run
Zope, I got this exception:
OverflowError: signed integer is greater than maximum
In the archives I encounter no solutions. This is what I could find, so
I share with you all:
It seems that on 64bit platforms, sys.maxint is much greater than list's
insertion maximum index. I'm not sure if this a bug in python or a
logical bound ---given the amount of RAM it would take to insert
9,223,372,036,854,775,807 items ;)--- Maybe a bug in the documentation,
though
However, Archetypes.Schema.moveField method documents the use of maxint
for inserting at the end of the Schema::
maxint can be used to move the field to the last position possible
>>> from sys import maxint
>>> spos = schema.copy()
>>> spos.moveField('a', pos=maxint)
>>> spos.keys()
['b', 'c', 'a']
I have seen this usage in some products. This raises and OverflowError
on 64bit platforms.
The fix is simple in the code of the caller::
from sys import maxint
if maxint >> 33: # Am I running on 64bits?
maxint = maxint >> 33
theschema.moveField(the_name, pos=maxint)
Now, the maxint variable holds an acceptable value.
I think the docstring should be appended with a "Note: On 64bits
platform this raises an OverflowError blah blah..."
Best regards,
Manuel.
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