sub sieve {
  my @pats = UNIVERSAL::isa($_[0], 'Regexp') ? @_ : map(qr/$_/, @_);

  sub {
    my %slots;
    $slots{$_} = [] for @pats, "";

    my $cref = UNIVERSAL::isa($_[0], 'CODE') && shift;

    ITEM:
    for (@_) {
      my $k = $cref ? $cref->() : $_;
      for my $p (@pats) {
        push(@{ $slots{$p} }, $_), next ITEM if $k =~ /$p/;
      }
      push @{ $slots{""} }, $_;
    }

    return map @$_, @slots{@pats, ""};
  }
}


my %tapes = (...);
my $c5p5 = sieve(qr/-C5$/, qr/-P5$/);
my @sorted_keys = $c5p5->(sub { $tapes{$_} }, keys %tapes);