How to use Getters and Setters in Ruby

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Getter and Setter methods in Ruby are gateways to access class instance variables. In this blog post I will explain how to create a class with getter and setter methods.

Let’s explain what a getter and a setter method in Ruby are!

A Getter method is the only way where you can retrieve the value of an instance variable from outside its class. A Setter method is the only way where you can assign a value to an instance variable from outside its class.

Now that we have an idea on what each one is, let’s explain them using an example.

Here is a Student class:

class Student
  def initialize(name)
    @name = name
  end
end

student = Student.new('Sarah')
p student.name #=> undefined method `name' (NoMethodError)

We defined a Student class and then later on we created a student giving her the name “Sarah”, however when we tried to access the student name, it gave us a NoMethodError because it is trying to look for a method called name but we never defined this method.

As we said before, we need to define a getter method to be able to retrieve the student name:

class Student
  def initialize(name)
    @name = name
  end

  #getter method
  def name
    @name
  end
end

student = Student.new('Sarah')
p student.name #=> "Sarah"

Here we were able to retrieve the name because we defined a getter method for the name instance variable.

Now, let’s try to change the name of the student:

class Student
  def initialize(name)
    @name = name
  end

  #getter method
  def name
    @name
  end
end

student = Student.new('Sarah')
p student.name #=> "Sarah"
student.name = 'Pumpkin' #=> undefined method `name='(NoMethodError)

Here when we tried to assign another name to the student, we got a NoMethodError because we never defined a setter method for the name instance variable.

Here is how we define a setter method:

class Student
  def initialize(name)
    @name = name
  end

  #getter method
  def name
    @name
  end

  #setter method
  def name=(name)
    @name = name
  end
end

student = Student.new('Sarah')
p student.name #=> "Sarah"
student.name = 'Pumpkin'
p student.name #=> "Pumpkin"

Notice how we defined the setter method adding = to the end of its name to indicate it is a setter method. When we do student.name = 'Pumpkin' this will automatically call the setter method sending whatever is after the equal sign = to the method as a parameter.

Hope that gave you a clear explanation on Getters and Setters in Ruby. If you would like to add anything, please comment below!