On Sat, 21 May 2011 15:55:56 -0700, John Nagle wrote: > On 5/19/2011 11:33 PM, Ulrich Eckhardt wrote: > >> For that reason, it is generally useful to use immutable types like >> integers, floats, strings and tuples thereof as keys. Since you can't >> change them, you basically have the guarantee that they hash the same. > > Right. It's something of a lack that Python doesn't > have user-defined immutable objects.
Although it's not that hard to write your own immutable (-ish) objects. http://northernplanets.blogspot.com/2007/01/immutable-instances-in-python.html Or see the Decimal and Fraction classes in the standard library. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
