Thanks for the advice. Once assured that __hash__ etc was the right route, I found that using hash() instead of object.__hash__() gave me stable hash valules. (I am hashing strings that I know to be unique.)
The "no luck" situation was that a set would accept the same object multiple times, not recognizing that it was truly the same object. Nick Vatamaniuc wrote: > JK, > > You are correct to implement __hash__ and __eq__. The problem is how > you implemented them. Usually your __eq__ method should compare the > necessary attributes of the objects for equality. The __hash__ should > return a 32-bit integer. Your best bet is probably to return a hash of > hashes of your attributes that are used in equality comparison. What > this means is that your attributes used to produce the __hash__ should > also be hashable. This is important yet not immediatly obvious. So you > could for example return hash( (attribute1, attribute2, attribute3) ), > where attribute1, attribute2, attribute3 are all hashable. > Of course, you provided no code and no error messages (the > 'SoFarNoLuck' exception is not descriptive enough ; ) > > Hope this helps > > > > JKPeck wrote: > > I would like to be able use sets where the set members are objects of a > > class I wrote. > > I want the members to be distinguished by some of the object content, > > but I have not figured out how a set determines whether two (potential) > > elements are identical. I tried implementing __eq__ and __ne__ and > > __hash__ to make objects with identical content behave as identical for > > set membership, but so far no luck. > > > > I could subclass set if necessary, but I still don't know what I would > > need to override. > > > > TIA for any advice you can offer. -- http://mail.python.org/mailman/listinfo/python-list
