Key Concepts

Review core concepts you need to learn to master this subject

Ruby Class Variables

Ruby .new Method

Ruby Instance Variable

Ruby initialize Method

Ruby Class

Ruby super Keyword

Ruby attr_reader attr_writer Methods

Ruby Class Variables

class Child
  @@children = 0
  def initialize(name, birth_year)
    @name = name
    @birth_year = birth_year
    @@children +=1
  end

  def self.children_added
    return @@children
  end

end

naomi = Child.new("Naomi", 2006)
bertha = Child.new("Bertha", 2008)

puts Child.children_added # => 2

In Ruby, class variables are attached to the class in which they are declared. A class variable should be declared with two @ symbols preceding it.

Object-Oriented Programming I
Lesson 1 of 2