Attribute Accessors

Attribute accessors provide us with a streamlined way to define getters and setters for instance variables. Otherwise, they are left private.

Let’s say that you have a class with instance variables and you want to expose them to the outside world:

class Food
  def initialize(protein)
		# this instance variable cannot be accessed from outside
    @protein = protein
  end
end

bacon = Food.new(25)
bacon.protein # NoMethodError: undefined method `protein'

To solve this, we'd define a getter and setter:

class Food
	# getter
	def protein
		@protein
	end
	# setter
	def protein=(value)
		@protein = value
	end
end

Lucky for us, Ruby provides attribute accessors so we don't have to do this by hand.

class Food
	attr_accessor :protein, :calories
	def initialize(protein, calories)
		@protein = protein
		@calories = calories
	end
end

Above, we are having 4 new methods defined for us:

1. protein
2. protein=
3. calories
4. calories=

---

• attr_reader - generate getter
• attr_writer - generate setter
• attr_accessor - generate getter and setter