You can also use a sieve. It's potentially faster than a complicated sort() algorithm to place things matching certain patterns before others. 
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);

[download]
I hope it's clear what I'm doing. I create a sieve by passing a list of patterns in the order of importance. Then I use that code reference (returned by sieve()) to "sort" a list. I can pass a code block as the first argument to determine what I do to the strings being passed to the sieve. In this case, even though I'm sorting the keys of the hash, I want to do the regex comparison to $tapes{$_}.

P.S. this looks much prettier in Ruby.

Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart

In reply to Re: Crazy hash sorting issue. by japhy
in thread Crazy hash sorting issue. by rementis

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.