use mro          qw( );
use Scalar::Util qw( blessed );

sub get_package {
   my ($obj, $method_name) = @_;
   defined( my $class = blessed($obj) )
      or return undef;

   for my $pkg_name (@{ mro::get_linear_isa($class) }) {
      my $pkg = do {
         no strict qw( refs );
         *{ $pkg_name.'::'.$method_name }
      };
      return $pkg_name if *{$pkg}{CODE};
   }

   return undef;
}

##</code><code>##

use B qw( svref_2object );

sub get_package {
   my ($obj, $method_name) = @_;
   my $method_ref = $obj->can($method_name)
      or return undef;

   return svref_2object($method_ref)->GV->STASH->NAME;
}

##</code><code>##

use B qw( svref_2object );

sub get_package {
   my ($obj, $method_name) = @_;
   my $method_ref = $obj->can($method_name)
      or return undef;

   return svref_2object($method_ref)->FILE;
}