package NewObj;
sub new { return bless {},$_[0] };

package Foo;
our @ISA=qw(NewObj);
sub call_bar {
  my ($self,$bar)=@_;
  $bar->who_called;
}

package Bar;
use strict;
use warnings;

use overload; #VITAL!

our @ISA=qw(NewObj);
sub who_called {
  my ($self)=@_;
  package DB;
  unless (my (undef,undef,undef,$sub)=caller(1)) {
  	print "Called from main\n";
  } else {
    print "Called from $sub\n";
    if (ref($DB::args[0]) and overload::StrVal($DB::args[0])=~/=/) {
    	
    	print "\tWhich is a method that was invoked on ".overload::StrVal($DB::args[0])."\n";
    } else {
    	print "@DB::args";
    }
  }
}

package main;

my $obj1=Foo->new();
my $obj2=Bar->new();
print "OBJ1 (Foo) : ".overload::StrVal($obj1)."\n"
$obj1->call_bar($obj2);