#!/usr/bin/perl
use strict;
use warnings;

BEGIN {
   package Foo;

   sub method {
       routine();
   }

   sub routine {
       return __PACKAGE__;
   }
}

BEGIN {
   package Foo::Bar;
   our @ISA = qw( Foo );

   sub routine {
       return __PACKAGE__;
   }

   sub method {
       no warnings 'redefine';
 
       # Temporarily override routine() in the parent class.
       local *Foo::routine = \&routine;
    
       # Delegate to parent method.
       my $self = shift;
       $self->SUPER::method(@_);
   }
}

print "Foo:      ", Foo->method, "\n";
print "Foo::Bar: ", Foo::Bar->method, "\n";
print "Foo:      ", Foo->method, "\n";