sub sort
{
   my ( $self, $sort_spec ) = @_;
 
   my $sort_done = 0;
 
   if ( defined $sort_spec )
   {
 
     my @sort_objs;
 
     foreach my $obj ( @{$self->{_data}} )
     {
       my $sv = [];
       push @{$sv}, $obj->factory_index();
 
       foreach my $spec ( @{$sort_spec} )
       {
         my $meth = $spec->{Key};
         push @{$sv}, $obj->$meth();
       }
 
      push @sort_objs, $sv;
 
     }
 
 
     my @comparisons = ();
 
     my $index = 0;
 
     foreach my $spec ( @{$sort_spec} )
     {
       $index++;
       my $comp = '';
       my ($left_arg, $right_arg) = ('$a','$b');
 
       if ( exists $spec->{Direction} and $spec->{Direction} eq '-' )
       {
          ( $left_arg, $right_arg) = ('$b', '$a');
       }
 
       if ( $spec->{Compare} eq 'cmp' || $spec->{Compare} eq '<=>' )
       {
          $comp = "${left_arg}->[$index] $spec->{Compare} ${right_arg}->[$index]";
       }
       else
       {
         $comp = "$spec->{Compare}(${left_arg}->[$index],${right_arg}->[$index])";
       }
 
       push @comparisons, $comp;
 
     }
      
     if ( $index )
     {
       my $sub = join ' || ' , @comparisons;
 
       $sub = "sub { $sub  };";
 
       *sortsub = eval $sub;
 
       $self->{_sort_index} = [];
 
       @{$self->{_sort_index}} = map { $_->[0] }
                                 sort sortsub  @sort_objs;
       
       $sort_done = 1;
 
       my $index = 0;
 
       foreach my $obj ( $self->list() )
       {
          $obj->factory_index($index++);
       }
 
     }
   }
 
  return $self->{_sorted} = $sort_done;
 
}