title: How do I write a writer method for a class variable in Ruby?
body: <p>I'm studying Ruby and my brain just froze.</p>
  
  <p>In the following code, how would I write the class writer method for 'self.total_people'? I'm trying to 'count' the number of instances of the class 'Person'.</p>
  
  <pre><code>    class Person
  
       attr_accessor :name, :age
  
   @@nationalities = ['French', 'American', 'Colombian', 'Japanese', 'Russian', 'Peruvian']
  
   @@current_people = []
  
   @@total_people = 0
  
  def self.nationalities #reader
     @@nationalities
   end
  
   def self.nationalities=(array=[]) #writer
     @@nationalities = array
   end
  
   def self.current_people #reader
     @@current_people
   end
  
   def self.total_people #reader
     @@total_people
   end
  
  def self.total_people #writer
    #-----?????
  end
  
  
  
   def self.create_with_attributes(name, age)
     person = self.new(name)
     person.age = age
     person.name = name
     return person
   end
  
  
   def initialize(name="Bob", age=0)
     @name = name
     @age = age
     puts "A new person has been instantiated."
     @@total_people =+ 1
     @@current_people &lt;&lt; self
   end
  </code></pre>