#! /usr/bin/perl
use warnings; use strict;
use HTML::Template;
use Data::Dumper;

my $text = "<TMPL_LOOP foo>bar=<TMPL_VAR bar>\n</TMPL_LOOP>";

my $template = HTML::Template->new(scalarref => \$text,
                                   loop_context_vars => 1);
$template->param(foo => [{bar => 10}, {bar => 20}]);

my $array_ref = $template->param('foo');
if ($array_ref) {
    print Dumper($array_ref);
    print Dumper($array_ref->[1]);
    #
    # add a new element
    #
    push (@$array_ref, {bar => 30});

    $template->param(foo => $array_ref);
}
print $template->output;