package Foo;
use strict;
use Data::Dumper;

sub new {
    my $class  = shift;
    my ( $package ) = caller;
    my $objref = { _package  => $package };
    bless $objref, $class;
}

sub list_params {
    my ( $self, $cgi ) = @_;
    my %formdata;

    # Use this if OO CGI
    if ( ref $cgi eq 'CGI' ) {
        foreach my $key ( $cgi->param ) {
            my @vals = $cgi->param( $key );
            $formdata{ $key } = _format_vals( \@vals );
        }
        
    # Function-oriented CGI
    } elsif ( $cgi ) {
        {
            # Don't try this at home, kids
            no strict qw/ refs subs /;
            my $_param = $self->{ '_package' }.'::param';
            my $package = \%{$self->{ '_package' } . '::'};

            # Looks like a function oriented call but 'param' was not exported
            if ( ! exists $package->{ 'param' } ) {
                return 0;
            }

            foreach my $key ( eval $_param ) {
                my $_param_call = $_param . "($key)";
                my @vals = eval $_param_call;
                $formdata{ $key } = _format_vals( \@vals );
            }
        }
    } else {
        return 0;
    }
    Dumper( \%formdata );
}

sub _format_vals {
    my $vals = shift;
    @$vals == 1 ? @$vals[ 0 ] :
    ! @$vals    ? undef       :
                  $vals;
}
"Ovid";