Privileged methods CoffeeScript

privileged_methods.coffee

class Person
  
  constructor: (name)->
    @name = name

  # private method
  greet_p = (person = {}) ->
    msg = if person.hasOwnProperty 'name' 
      "Hi #{person.name}"
    else
      "Hi"
    "#{msg}, I'm #{@name}"

  # privileged method
  greet: (person)->
    greet_p.call this , person

console.log '***'

john = new Person 'John'
bob  = new Person 'Bob'

console.log john.greet()     # Hi, I'm John
console.log bob.greet()      # Hi, I'm Bob

console.log john.greet bob   # Hi Bob, I'm John
console.log bob.greet john   # Hi John, I'm Bob

console.log john.greet_p()   #  Object #<Person> has no method 'greet_p'