metaparameters on hiera-defined resources

foobar.pp

class foobar (
  Hash[String,
       Struct[{
         attributes => Hash[String, Data],
         Optional[requires] => Hash[String, String],
         Optional[notifies] => Hash[String, String]
       }]] $files,
  Hash[String, Data] $file_defaults = {},
) {
  $files.each |$key, $value| {
    $requires = $value['requires'].reduce([]) |$memo, $x| { $memo + [Resource[$x[0]][$x[1]]] }
    $notifies = $value['notifies'].reduce([]) |$memo, $x| { $memo + [Resource[$x[0]][$x[1]]] }
    file {
      $key:
        * => $value['attributes'],
        require => $requires,
        notify  => $notifies,
      ;
      default:
        * => $file_defaults,
      ;
    }
  }
}

hieradata.yaml

---
foobar::files:
  '/etc/foo':
    attributes:
      ensure: 'file'
      owner: 'root'
      group: 'root'
      mode: '0640'
    requires:
      package: 'foo'
    notifies:
      service: 'foo'
  '/etc/bar':
    attributes:
      ensure: 'directory'
      owner: 'bar'
      group: 'bar'
      mode: '0750'
  '/etc/bar/bar.conf':
    attributes:
      ensure: 'file'
      owner: 'bar'
      group: 'bar'
      mode: '0640'
    requires:
      package: 'bar'
    notifies:
      service: 'bar'