abigail wrote >On Fri, Apr 05, 2002 at 12:17:27AM +0300, Ilmari Karonen wrote: >> >> > I must say however, that requiring that the array is passed as a >> > reference seems an oddity to me. If you pass it a list, it should, >> > IMO, return the shuffled list. >> >> The point of taking a reference is that the Fisher-Yates algorithm is an >> in-place shuffle. If your array happens to be a couple of megabytes in >> size, you start to appreciate this feature. So, since we have this nice >> in-place shuffle algorithm, which is just as simple and effective as any >> non-in-place alternative could ever be, it seems silly to start making >> copies of arrays just to satisfy Perl's return-by-value semantics. > >Ah, well, one could give the same argument for sort and map, but >noone seems to object to them not performing in situ operations. >
This is not true, I remember discussions about in-place-sort some weeks ago in this list. Apart from that, I feel many people (rightly) just expect sort to work in situ, and are puzzled to see sort @a in a void context not having the desired effect. >> In any case, if you want to shuffle a copy of an array, you can -- just >> make the copy before shuffling it. Sure, it's a little extra work, but >> it's no worse than what you have to do with s///. Turning an in-place >> shuffle into copy-and-shuffle is easy, the other way is impossible. > >Impossible? I wonder how people manage to sort arrays then.... > > @array = shuffle @array; # Tada! This is not an in-place-shuffle. The array is copied, shuffled, and copied back in that process. (Or am I missing some magic here?) Joachim -- there is only one way to do it
