Re: Finding oldest file in directory

[Roy Johnson]

Finding the oldest/most recent/minimum/maximum of a list does not require sorting. For a 10-file directory, it's not a big deal, but the right tool for the job is a simple max-finder:

my $oldest;
my $oldtime = 0;
for (glob "$dir/*.pl") {
  my $thistime = -C;
  if ($thistime > $oldtime) {
    ($oldest, $oldtime) = ($_, $thistime);
  } 
}

You could do this at kind of the same programming level as you're trying to by using List::Util 'reduce':

use List::Util 'reduce';
my $file = (reduce {$a->[0] < $b->[0] ? $a : $b}
                   map {[(stat)[10],$_]}
                   glob '*.pl'
           )->[1];

That makes for somewhat complicated reading, though, and might be better broken into more steps.

Update: for posterity: the map above is only useful for reducing the number of times stat is called, from 2*N to N. The overhead of map and storing the values and dereferencing is probably not worth it. It's certainly simpler to say

my $file = reduce {(stat $a)[10] < (stat $b)[10] ? $a : $b}
                  glob '*.pl';