Question

I get nil, nil but I expected the result to be 9, ‘My Soduko’

class Soduko
  attr_accessor :name, :rows, :columns
  def initialize
    rows = 9
    columns = 9
    name = 'My Soduko'
  end
end

new_soduko= Soduko.new
puts new_soduko.rows
puts new_soduko.name

$ ruby soduko.rb 
nil
nil

I thought new would use the initialize method and set those attributes?

Answer 1

What you need is an instance variable in the initialize method. You create an instance variable by prefixing the name with @. When you make a new Soduko object with new_soduko= Soduko.new you want to set instance variables for that particular object. Without the @ you have just created local variables in the initialize method.

class Soduko
  attr_accessor :name, :rows, :columns
  def initialize
    @rows = 9          # adding @ makes these instance variables.
    @columns = 9
    @name = 'My Soduko'
  end
end

new_soduko= Soduko.new
puts new_soduko.rows
puts new_soduko.name