Ruby Build an Address Book in Ruby Class Design Contact Class: Part 2

Nafeez Quraishi
Nafeez Quraishi
8,524 Points

last_first giving undefined method slice error

I wrote the method slightly differently than what is shown on the tutorial and i am getting undefined method error. Could someone please point what is wrong with the below way-

def last_first

    last_first = last_name
    last_first += ", "
    last_first += first_name
    last_first += " "
    if !middle_name.nil?
      middle_name = middle_name.slice(0, 1)
      last_first += middle_name
      last_first += "."


Error i'm getting is:

AddressBook/Contact.rb:37:in `last_first': undefined method `slice' for nil:NilClass (NoMethodError)

2 Answers

Jay McGavren
Jay McGavren
Treehouse Teacher

If it's saying undefined method 'slice' for nil:NilClass, that means middle_name is getting set to nil. I think this is happening because your variable names are getting confused with your method names.

Below is my updated version of your code, with comments added.

class Contact

  # I don't have your full code, so I created this
  # simplified version. Hopefully this is correct.
  attr_accessor :last_name, :first_name, :middle_name

  def last_first
    # It's not a good idea to use a variable with the same
    # name as a method. Sometimes it will work, but it risks
    # accidentally calling a method when you're just trying
    # to assign to the variable.
    # I renamed the variable.
    full_name = last_name
    full_name += ", "
    full_name += first_name
    full_name += " "
    if !middle_name.nil?
      # Here, I'm pretty sure your code IS calling the
      # middle_name= method and overwriting it with just
      # the initial. I changed the variable name here, too,
      # and that seems to have fixed it.
      middle_initial = middle_name.slice(0, 1)
      full_name += middle_initial
      full_name += "."



contact =
contact.last_name = "Last"
contact.first_name = "First"
contact.middle_name = "Middle"
puts contact.last_first # => Last, First M.