Sort Perl array in place

Question

I have a reference to an array (called $intervals) and I would like to sort the values in this array. It\'s possible that there could be a huge number of values

Answer 1

Since Perl 5.8.4, the in-place sort @a = sort @a is optimized. See the links below for details:

Performance Enhancements in perl584delta

http://perl5.git.perl.org/perl.git/commit/fe1bc4cf71e7b04d33e679798964a090d9fa7b46?f=pp_sort.c

+    /* The optimiser converts "@a = sort @a" to "sort \@a";
+     * in case of a tied @a, pessimise: push (@a) onto stack, then assign
+     * the result back to @a at the end of this function */

So you should be able to write:

@$intervals = sort by_position @$intervals

And in Perl's later than 5.8.3 you will see reduced memory usage (and preservation of aliasing for the rare times it matters).