TheDamian discusses this in his book, Object Oriented Perl. In a nutshell, Perl has no equivalent to C++'s static (or Java's for that matter), but you can achieve roughly the same effect with properly scoped lexical variables:

use strict;

my @foo;
push @foo, Foo->new() for (0..4);

package Foo;

{
   my $count = 0;
   sub get_count { return $count }
   sub inc_count { return ++$count }
}

sub new { 
   my $class = shift;

   $class->inc_count();
   print STDERR 'there are ', $class->get_count(), " instances\n";

   my $self  = {
      bar => 42
   };
   return bless $self, $class;
}
[download]

UPDATE:
Very good point perrin. Try adding the following code snippet in perrin's example and my example after the for loop line to see the difference in action:

print $Foo::count, "\n";
[download]

The methods get_count() and inc_count() are still accessible to the client in my code, by the way. That is not necessarily a good thing ...

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)