On Oct 12, 2006, at 2:43 PM, Patrick K. O'Brien wrote:

> Patrick K. O'Brien wrote:
>>
>> P.S.  There are other tests that are similarly broken.
>
> On a similar note, PersistentSet needs to have the following method
> added to its definition:
>
>     def __hash__(self):
>         raise TypeError("PersistentSet objects are unhashable")


We've gone back and forth on this question, but I think
we don't need this method.  It is a trade-off as to whether
PersistentSet should be more like set, or more like Persistent.

I think the best thing to do is remove the unit test
that verifies that PersistentSet and set hash the same way.
This is just one of several ways that they differ.

Similarly, PersistentList and PersistentDict are hashable,
but the types they wrap are not.