Instance Variables

Instance variables are available to the whole class and are created with @:

class Dog
  @name
end

@name isn't currently accessible from outside the class. Ruby uses a method named initialize to set up values when an object is created. (This is like Java's constructors.)

class Dog

    def initialize(name)
      @name = name
    end        

    #getter
    def name
        @name
    end

    def bark
        puts "Woof!"
    end
end

Note the method name above. This lets code outside the class get the value of @name.¹

We can now create a Dog:

doggy = Dog.new("Max")  #creates new Dog named "Max"
puts doggy.name  #calls Dog's `name` method, which returns @name

This prints out:

Max

^{1. Ruby also provides shortcuts for creating methods to access and change variables; see Ruby Classes.}

Challenge

Copy your simple Product class form before and make it useful:

1. Inside your Product class, create an initialize method that takes in 2 parameters and assigns their values to 2 instance variables named @name and @description.
2. Create 2 'getter' methods to return the value of @name and @description.
3. Change your method to_s so it returns something more useful: the name of the product followed by the description. For example, a product named "Pencil" with a description "Writing implement" should return "Pencil Writing implement".

Need help? Click on the hints you need below.