data.yaml

profile::bacula::myclass::mydefines:
  foobar:
    abc: some value

mydefine.pp

define profile::bacula::mydefine (
    $abc = undef
) {
    notice($abc)
}

y.pp

class profile::bacula::myclass(
 $mydefines = {}
 ) {
  $mydefines.each |$name, $mydefine| {
    profile::bacula::mydefines{ $name:
      * => $mydefine
    }
}