You could tie $":

#!/usr/bin/perl

use strict;
use warnings;

sub TIESCALAR {
    my $class = shift;
    bless [-1 => [@_]] => $class;
}

sub STORE {die}
sub FETCH {
    ${$_ [0]} [1] [${$_ [0]} [0] ++ % @{${$_ [0]} [1]}];
}

tie $" => main => ":", "-";

my @a = qw /0 1 0 1 0 1 0 1 0 1 0 1/;

print "@a\n";

__END__
0:1-0:1-0:1-0:1-0:1-0:1
[download]

Unfortunally, there are a couple of bugs in perl related to this. First is that it will do a bogus call to FETCH before interpolating (FETCH is called once too often). Second is that perl gets mighty confused if FETCH returns an empty string. (Which is unfortunally just what you want).

Abigail

---

---

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! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

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:
	&		&
	<		&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.