On Wed, 10 Jul 2013 16:54:02 +0100, Joshua Landau wrote: > On 10 July 2013 10:00, Steven D'Aprano <st...@pearwood.info> wrote: >> On Wed, 10 Jul 2013 07:55:05 +0000, Mats Peterson wrote: >> >>> A moderator who calls himself “animuson” on Stack Overflow doesn’t >>> want to face the truth. He has deleted all my postings regarding >>> Python regular expression matching being extremely slow compared to >>> Perl. >> >> That's by design. We don't want to make the same mistake as Perl, where >> every problem is solved by a regular expression: >> >> http://neilk.net/blog/2000/06/01/abigails-regex-to-test-for-prime- numbers/ >> >> so we deliberately make regexes as slow as possible so that programmers >> will look for a better way to solve their problem. If you check the >> source code for the re engine, you'll find that for certain regexes, it >> busy-waits for anything up to 30 seconds at a time, deliberately >> wasting cycles. > > I hate to sound like this but do you realise that this is exactly what > you're arguing for when saying that sum() shouldn't use "+="?
You're referencing an off-list conversation, which will probably confuse most others reading this. I don't agree with that. Apart from one throw-away comment where I said that sometimes it is handy to have a trivial example of an O(N**2) algorithm for teaching purposes, I have never made any suggestion that having sum(lists) be slow was a good thing in and of itself. My argument has always been that there are costs as well as benefits to changing sum of lists to use += instead of + and I'm not convinced that the benefits outweigh those costs. Quite frankly, looking at the pure-Python version of sum that Sergey has posted, I *really* hope he is a better C programmer than Python programmer, because his pure-Python version is so full of bugs it is ridiculous. But now I'm also referring to posts off-list :-) -- Steven -- http://mail.python.org/mailman/listinfo/python-list
