# Interface
$ro->execute('init');
if( $ro->param ){
   $ro->execute('control');
}
else{
   $ro->execute('browse');
}
$ro->execute('trailer');

# im Attribute {IF} liegen die Codereferenzen
sub execute{
    my $self = shift;
    my $key  = shift;
    $self->{IF}{$key}->($self);
}