my $filter = sub {
     my $text_ref = shift;
     $$text_ref =~ s/!!!ZAP_(.*?)!!!/<TMPL_$1>/g;
   };

   # open zap.tmpl using the above filter
   my $template = HTML::Template->new(
                    filename => 'zap.tmpl',
                    filter => $filter);

##</code><code>##

sub convert {
   my $text_ref = shift;
   $$text_ref =~ s/\[\%=(.*?)\%\]/<TMPL_VAR NAME=$1>/g;
   $$text_ref =~ s/\[\%\/(.*?)\%\]/<\/TMPL_$1>/g;
   $$text_ref =~ s/\[\%(.*?)\%\]/<TMPL_$1>/g;
}