More like this

fooaf.pp

contain foo::package
contain foo::config
contain foo:service

Class['foo::package']
-> Class['foo::config']
~> Class['foo::servce']

# package.pp
if $foo::manage_package {
  package { 'foo': 
    bar => bar,
    baz => baz
  }
}

foodh.pp

if $manage_package {
  contain foo::package
}

if $manage_service {
  contain foo:service
}

contain foo::config

if $manage_package {
  contain foo::package
  Class['foo::package'] -> Class ['foo::config']
}

if $manage_service {
  contain foo:service
  Class['foo::config'] ~> Class ['foo::service']
}

contain foo::config