I'm not quite sure how to make these lvalues, but you can generate accessor/mutator methods without using eval. Here's a quick example:

   foreach my $field (@required_fields)
   {
      no strict 'refs';
      chomp $field;
      *$field = sub {
          my $self = shift;
          if ($_[0]) { $self->{$field} = $_[0]; }
          else       { $self->{$field);         } 
      };
   }
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Note: I am not necessarily endorsing this type of hybrid mutator/accessor, just using it as an example.