There are a few design choices we could have made for sum(); in particular, for non-empty sequences we could not have used the identity element (the optional second argument). As it is, we get unjustified but understandable complaints that sum() "only supports numbers". An alternative design could have returned:
- the identity (defaulting to 0) if the sequence is empty - the first and only element if the sequence only has one element - (...(((A + B) + C) + D) + ...) if the sequence has more than one element This has surprises too (in particular of returning 0 when invoked without overriding the identity argument for a seqence of addable non-numbers) but works without using the second argument for a larger set of inputs I believe it is often used in such a way that the input is known to be non-empty). I'd be happy to be pointed to a past discussion where this was considered and rejected with a good reason; then I can post that to the blog (where the deficiency in sum() is being berated a bit excessively). -- --Guido van Rossum (home page: http://www.python.org/~guido/) _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
