example.pp

#
# init.pp
#
class foo(
  $name = 'bob',
  $age = 23,
  $occupation = 'self-employed',
  $job_description = 'nut scratcher'
) {

  # Do init stuff
}

#
# install.pp
#
class foo::install(
  # Inherit defaults from scoped module variables
  # While allowing overrides
  $occupation = $foo::occupation
  ) {

  # Do install stuff
  
  # Templates use local variables: just reassign them
  $name = $foo::name
  file { 'resume':
  content => template('foo/resume.erb'),
}

# resume.erb
Name = <%= @name %>
Occupation = <%= @occupation %>