[PyQt] Re: [PyKDE] Re: QAbstractItemModel 64 bit problem

[Phil Thompson]

I may be slow sometimes, but I'll get there in the end...

On Tuesday 26 September 2006 12:16 pm, Jeremy Sanders wrote:
> On Tue, 26 Sep 2006, Jeremy Sanders wrote:
> > The python Ids appear to be large integer values, e.g. 183006915920, but
> > when they are returned from internalId(), then they come back as negative
> > values e.g., -1676677808L, which don't even appear to match the bit
> > pattern of the original value.
>
> I'm afraid I'm replying to my own posting, but here is a short program to
> demonstrate the issue:
>
> ---------------------------------------------
> from PyQt4.QtCore import *
> from PyQt4.QtGui import *
>
> class C(QAbstractItemModel):
>      pass
>
> a = C()
> i = id(a)
> index = a.createIndex(0, 0, i)
>
> print index.internalId(), i
> ---------------------------------------------
>
> On 32 bit x86 this prints:
>
> -1208606100 -1208606100
>
> On 64 bit x86_64 this prints
>
> -1788599016 182894994712
>
> I couldn't see this mentioned in the mailing list archive.

This is the correct behaviour.

On 64 bits int is 4 bytes and long and void* are 8 bytes. Python ints are 
actually C longs. The value of id() is greater than 4 bytes so you lose bits 
when you call createIndex().

Phil