my $l = new z;

$l->{xxx4} = 'wrong way';

my $str = 'xxx';
my $str1 = "4";
my $str2 = "param1";

eval ("print \$l->$str$str1(\$str2)");

package z;

sub new
   {
   my $class = shift;
   my $self = {};
   return bless $self, $class;
   };

sub xxx4
   {
   my $self = shift;
   my $param = shift;
   return "were requested xxx4: $param \n";
   };