[Python-Dev] Retrieve an arbitrary element from a set without removing it
tjreedy at udel.edu
Sat Oct 24 21:37:13 CEST 2009
Guido van Rossum wrote:
> On Sat, Oct 24, 2009 at 10:34 AM, Alexander Belopolsky
> <alexander.belopolsky at gmail.com> wrote:
>> To me, however, a set seems to be a container that is a specialization
>> of a dict with values and keys being the same.
> That's absurd; the mapping provides nothing useful.
Given Alexander's premise, I agree with your response. But his premise
is wrong. Python's current builtin set class maps abstract equivalence
classes to representative members. And this *is* useful. Mapping
arbitrary members of such classes to representative members, sometimes
called 'canonical', is a standard problem/goal in math. String interning
is an application of this idea.
Terry Jan Reedy
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