namevar.pp

file { 'long_ass_filename':
  ensure => file,
  path   => '/var/www/some/really/freaking/long/path/name/do_you_want_to_repeat.html',
}

service { 'some_service':
  ensure    => running,
  subscribe => File['long_ass_filename'],
}

no-namevar.pp

file { '/var/www/some/really/freaking/long/path/name/do_you_want_to_repeat.html':
  ensure => file,
}

service { 'some_service':
  ensure    => running,
  subscribe => File['/var/www/some/really/freaking/long/path/name/do_you_want_to_repeat.html'],
}