I'm using a custom ENC which we are using to dump a yaml file based on an internal configuration wrapper. I want the ability to specify a parameter (variable) in the top scope and allow it to be be a default variable of a class. At this point, my research shows me this is not a bad idea

enc.yaml

classes:
  rsyslog::client:
     port: 1234
parameters:
  server: my-rsyslog-server

sample.pp

# This patterns supports defaulting a class scoped variable to the first scope level variable it comes across.
# If I wanted to explicitly check only the top level scope, I would do $::server

class rsyslog::client(
  $server => $server,   # $server = $server || undef
  $port   => $port ? {  # $port = $port || '514'
    ''      => '514',
    default => $port
  }
) {

  if !defined($server) { fail "server must be defined" }

  notify { "The server is ${server}": }
  notify { "The port is ${port}": }

}