I like to version my files automatically by the CVS revision number. Here's how to handle that in Perl:

package Class::Cache;
use strict;

BEGIN {
    use Exporter ();
    use vars qw($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);
    $VERSION     = ('$Revision: 1.1.1.1 $' =~ m/([\.\d]+)/) ;
    @ISA         = qw(Exporter);
    #Give a hoot don't pollute, do not export more than needed by defa
+ult
    @EXPORT      = qw();
    @EXPORT_OK   = qw();
    %EXPORT_TAGS = ();
}
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