Another optimization, using eval

my @dlcopy = @dir_list ;
my @extensions = qw(zip log whatever) ;
my %matches ;

foreach my $ext (@extensions) {
  my $nonmatching = [] ;
  my $matching    = [] ;
  my $code = q|
  foreach my $file (@dlcopy) {
    push @{$file =~ /\\.|.$ext.q|$/ ? $matching : $nonmatching},$file 
+;
  }
| ;
  # warn "DEBUG:$code" ;
  eval $code ;
  if ($@) {
    die "Something went wrong: $@" ;
  } else {
    @dlcopy = @$nonmatching ;
    $matches{$ext} = $matching ;
  }
}
[download]

This one further optimizes the pattern matching, dynamically creating the inner foreach with the pattern hardcoded (and not reevaluated at each cycle). This could be a great enhancement if you are matching a number of files that is far greater than the number of extensions (since you would have a few evals and a lot of "constant" pattern matchings)

Ciao!
--bronto

# Another Perl edition of a song:
# The End, by The Beatles
END {
  $you->take($love) eq $you->make($love) ;
}