package A;

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

sub _exe {
   my ($self,$a) = shift;
   $self->$a->(); # probably wrong !!

}



package B;

use base 'A';

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

sub _what {
   my ($self,$y) = shift;
   ## HERE I would like to pass _print() with $y (let it be a string) 
   ## to package A, method _exe() so that it executes
   ##  _print($y) in B.... Is this possible??

}


sub _print {
   my ($self,$x) = shift;
   print "$x\n";

}