Fixed Re: [ZODB-Dev] Help!

[JohnD.Heintz]

After learning a lot more about __cmp__(self, other) I can report back th=
at=20
everything is working.

We had insufficient handling for when __cmp__ was called on newly created=
=20
Persistent objects.  We had __hash__ working correctly, but the way BTree=
s=20
worked didn't bother with that.

For everyone benifit I've included our HashablePersistent code.  Please l=
et=20
me know if I've messed anything else up, but it seems to be working for u=
s.

John
class HashablePersistent(Persistent):
    def __hash__(self):
        """
        Trivial __hash__ implementation to get identity
        """
        if not self._p_oid:
            someGlobal.ensurePid(self)
        result =3D hash(self._p_oid)
        return result

    def __cmp__(self, other):
        if self._p_oid is None:
            someGlobal.ensurePid(self)

        if id(self) =3D=3D id(other):
            return 0

        if other is None:
            return -1
       =20
        try:
            if other._p_oid is None:
                someGlobal.ensurePid(other)

            return cmp(self._p_oid, other._p_oid)
        except AttributeError:
            return 1



On Wednesday 15 August 2001 18:07, John D. Heintz wrote:
> The following code raises an AssertionError because the BTree doesn't u=
se
> the Python defined __hash__ methods.
>
> Should I log this as a Collector bug or am I doing something wrong?
>
> John
>
>
> import ZODB
> from BTrees.OOBTree import OOBTree
> from ZODB import Persistence
>
> class HashablePersistent(Persistence.Persistent):
>     """
>     """
>     def __init__(self):
>         self.__version =3D "1.0"
>         self.hashCalled =3D 0
>
>     def __hash__(self):
>         """
>         Trivial __hash__ implementation to get identity
>         """
>         self.hashCalled =3D 1
>         return 5
>
>     def __cmp__(self, other):
>         return 0 # I know this needs to be implemented
>
> p =3D HashablePersistent()
> dict =3D {}
> dict[p] =3D p
> assert p.hashCalled
>
> p =3D HashablePersistent()
> btree =3D OOBTree()
> btree[p] =3D p
> assert p.hashCalled # !!This fails!!

--=20
=2E . . . . . . . . . . . . . . . . . . . . . . .

John D. Heintz | Senior Engineer

1016 La Posada Dr. | Suite 240 | Austin TX 78752
T 512.633.1198 | jheintz@isogen.com

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