=item @names = $form->param

=item @values = $form->param( $name )

=item $form->param( $name, $value, ... )

=item $form->param( $name, \@values )

Alternative interface to examining and setting the values of the form.

If called without arguments then it returns the names of all the
inputs in the form.  The names will not repeat even if multiple inputs
have the same name.  In scalar context the number of different names
is returned.

If called with a single argument then it returns the value or values
of inputs with the given name.  If called in scalar context only the
first value is returned.  If no input exists with the given name, then
C<undef> is returned.

If called with 2 or more arguments then it will set values of the
named inputs.  This form will croak if no inputs have the given name
or if any of the values provided does not fit.  Values can also be
provided as a reference to an array.  This form will allow unsetting
all values with the given name as well.

This interface resembles that of the param() function of the CGI
module.

=cut

sub param {
    my $self = shift;
    if (@_) {
        my $name = shift;
        my @inputs;
        for ($self->inputs) {
            my $n = $_->name;
            next if !defined($n) || $n ne $name;
            push(@inputs, $_);
        }

        if (@_) {
            # set
            die "No '$name' parameter exists" unless @inputs;
	    my @v = @_;
	    @v = @{$v[0]} if @v == 1 && ref($v[0]);
            while (@v) {
                my $v = shift @v;
                my $err;
                for my $i (0 .. @inputs-1) {
                    eval {
                        $inputs[$i]->value($v);
                    };
                    unless ($@) {
                        undef($err);
                        splice(@inputs, $i, 1);
                        last;
                    }
                    $err ||= $@;
                }
                die $err if $err;
            }

	    # the rest of the input should be cleared
	    for (@inputs) {
		$_->value(undef);
	    }
        }
        else {
            # get
            my @v;
            for (@inputs) {
		if (defined(my $v = $_->value)) {
		    push(@v, $v);
		}
            }
            return wantarray ? @v : $v[0];
        }
    }
    else {
        # list parameter names
        my @n;
        my %seen;
        for ($self->inputs) {
            my $n = $_->name;
            next if !defined($n) || $seen{$n}++;
            push(@n, $n);
        }
        return @n;
    }
}


=item $form->try_others( \&callback )

This method will iterate over all permutations of unvisited enumerated
values (<select>, <radio>, <checkbox>) and invoke the callback for
each.  The callback is passed the $form as argument.  The return value
from the callback is ignored and the try_others() method itself does