## package Base.pm ###
package Base;

sub new {

  my $class =  shift;

  my $self = {};

  bless $self, $class;

  return $self;

}

sub display {

  my $self = shift;

  print "This is Base display \n";

}

1;

## package Derived.pm ##

package Derived;
@ISA = qw (Base);

use Base;

sub new {

  my $class =  shift;

  my $self = {};
  print "this is Derived new \n";
  bless $self, $class;

  return $self;

}

sub display {

  my $self = shift;

  print "This is Derived display \n";

}

1 

## package Derived2.pm ### 

package Derived2;
use Derived;
@ISA = qw(Derived);
use mro;

sub new {

 my $class =  shift;

  my $self = {};

  bless $self, $class;

  return $self;

}

sub display {

  my $self = shift;

  print "This is Derived2 display \n";

}

1 


## Script.pl 

use strict;
use warnings;

use  mro ;

use Derived2;

my $obj = Derived2->new();

$obj->display(); #working as expected

my $gp = $obj->mro::get_linear_isa->[1];
my $gpm = $gp->can('display');

print "gp $gp |@$gp \n";
print "gp $gp |gpm $gpm \n";

$gp->display(); #does not work