Gustavo Narea wrote: > Hello again, everybody. > > Thank you very much for your responses. You guessed right, I didn't > use the __hash__ method (and I forgot to mention that, sorry). > > And unfortunately, I think I can't make them hashable, because the > objects are compared based on their attributes, which are in turn > other kind of objects compared based on other attributes. All these > class instances are compared with __eq__/__ne__ and they wrap > relatively complex data which would be hard to attempt to represent > them unambiguously using a 32-bit integer.
There is no need for hash to represent the data unambiguously. >>> hash(-1) -2 >>> hash(-2) -2 >>> hash(2.0**32 - 1) -2 >>> hash(1) 1 >>> hash(2.0**64 - 1) 1 >>> hash(2.0**64 + 1) 1 >>> hash(2) 2 >>> hash(1+2**32) 2 >>> hash(1+2**64) 2 >>> hash(1+2**128) 2 >>> hash(2.0) 2 The rule is, if x and y are equal, then hash(x) should equal hash(y). This does NOT imply that if hash(x) == hash(y), then x must equal y, nor is there any requirement for every unique piece of data to have a unique hash. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
