Chris Barker <chris.barker@noaa.gov> writes:
What I fail to see is why it's better to raise an exception and point users to a better way, than to simply provide an optimization so that it's a mute issue.
The only justification offered here is that will teach people that summing strings (and some other objects?) is order(N^2) and a bad idea. But:
a) Python's primary purpose is practical, not pedagogical (not that it isn't great for that)
b) I doubt any naive users learn anything other than "I can't use sum() for strings, I should use "".join()". Will they make the leap to "I shouldn't use string concatenation in a loop, either"? Oh, wait, you can use string concatenation in a loop -- that's been optimized. So will they learn: "some types of object shave poor performance with repeated concatenation and shouldn't be used with sum(). So If I write such a class, and want to sum them up, I'll need to write an optimized version of that code"?
I submit that no naive user is going to get any closer to a proper understanding of algorithmic Order behavior from this small hint. Which leaves no reason to prefer an Exception to an optimization.
One other point: perhaps this will lead a naive user into thinking -- "sum() raises an exception if I try to use it inefficiently, so it must be OK to use for anything that doesn't raise an exception" -- that would be a bad lesson to mis-learn....
AOL to that. Best, -Nikolaus -- GPG encrypted emails preferred. Key id: 0xD113FCAC3C4E599F Fingerprint: ED31 791B 2C5C 1613 AF38 8B8A D113 FCAC 3C4E 599F »Time flies like an arrow, fruit flies like a Banana.«