[Tutor] unhashable objects (unrelated to previous topic)
kent37 at tds.net
Mon Mar 28 05:52:55 CEST 2005
Orri Ganel wrote:
> Thanks to Jeff and John Fouhy . . . However, my question now is: can I
> treat Nodes sometimes the same and sometimes not? I want to treat
> Nodes whose cargo is the same the same everywhere *except* in a
> dictionary, because I want the user to be able to use LinkedList in a
> broader way than sets allow . . . In order to do this, I need my
> __hash__() method to treat Nodes differently than the rich comparison
> methods do. Is this a Bad Idea(tm) ?
The problem is, if you have two Nodes a and b where a == b, you will expect that for any dictionary
d[a] == d[b]. If Node.__eq__() has different semantics than Node.__hash__() this expectation will
not be correct.
More information about the Tutor