A fix for OverflowError in 64bits platforms
tjreedy at udel.edu
Thu Jul 3 22:11:21 CEST 2008
Manuel Vazquez Acosta wrote:
> Hi all,
> I'm debugging a Plone site in an AMD64 laptop. When I first tried to run
> Zope, I got this exception:
In general, versions numbers for both Python and the app are helpful.
> OverflowError: signed integer is greater than maximum
> In the archives I encounter no solutions.
Archives: Python? Zope? Plone?
> This is what I could find, so I share with you all:
I hope you have/will report this to the appropriate place.
> 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
This strikes me as an app bug. In any case, released versions of Python
will not change.
> 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,
> 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
This is a bit flakey. If they are going to use a surrogate for
len(schemalist)-1, they might as well accept anything larger and shrink
it to the proper value as slicing does.
> >>> 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..."
Better to fix it ;-)
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