use CGI;
my $q = CGI->new( { one => 1, two => 2, three => 3 } );
test(   map{$q->param($_)||"${_}_IS_NULL"}qw(one two three)  , 4 );
test( ( map{$q->param($_)||"${_}_IS_NULL"}qw(one two three) ), 4 );

sub test { $"=', ';print "Args( @_ )\n" }

__DATA__
Args( 1, 2, 3, 4_IS_NULL )
Args( 1, 2, 3, 4 )