[EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: >OKB (not okblacke) wrote: >> Fredrik Lundh wrote: >> > [EMAIL PROTECTED] wrote: [ ... ] >> >> > so what would an entry-level Python programmer expect from this >> >> > piece of code? >> >> > >> >> > for item in a.reverse(): >> >> > print item >> >> > for item in a.reverse(): >> >> > print item >> >> > >> >> I would expect it to first print a in reverse then a as it was. >> >> >> >> a=[1,2,3] >> >> >> >> I expect it to print >> >> >> >> 3 >> >> 2 >> >> 1 >> >> 1 >> >> 2 >> >> 3 >> > really? wouldn't >> > >> > 3 >> > 2 >> > 1 >> > 3 >> > 2 >> > 1 >> > >> > make a lot more sense ? >> Yes. The unintuitive thing is that the list is sorted in place at >> all. >intuitive seems to be a very subjective matter, depends on once >background etc :-)
A quick straw-poll of some non-Pythonistas (two sysadmins, two programmers) suggests that reversing in place is unintuitive -- all four expected: 3 2 1 3 2 1 as suggested by Fredrik. It was less clear-cut, talking through it, whether they found sorting inplace was intuitive or not, but it was agreed that it would be "odd" if sort() and reverse() behaved differently. All of which is to say I'm convinced by the current behaviour: 1. sort() in place makes sense in terms of space, and is not completely unintuitive. 2. reverse() should do what sort() does. 3. The inexperienced user is most likely to expect the above code to print 3 2 1 3 2 1, and is more likely to have difficulty tracking down the problem if reverse() returns self and they get unexpected results than if it returns None and they get a TypeError: iteration over non-sequence. -- \S -- [EMAIL PROTECTED] -- http://www.chaos.org.uk/~sion/ ___ | "Frankly I have no feelings towards penguins one way or the other" \X/ | -- Arthur C. Clarke her nu becomeþ se bera eadward ofdun hlæddre heafdes bæce bump bump bump
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