Understanding the Basics of Macros in Ruby Programming

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A big part of Ruby programming is based on making the programmer life’s easier and better. Macros in Ruby were created so programmers don’t write the same things over and over again. So what is a macro in Ruby?!

A macro in Ruby is a piece of code that is responsible for generating other code which could be a new instance method. In my previous blog post, I explained how to write Setter and Getter methods in Ruby. In this blog post, I will show you how you can use some macros that will generate getter or setter methods for you.

Macro for getter method

Let’s use the same Student class example from the last blog post:

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

  #getter method
  def name
    @name
  end
end

Ruby provides a way to include this getter method instead of always having to repeat the same thing. Here is how to do so:

class Student
  attr_reader :name #this replaces the getter method above
  
  def initialize(name)
    @name = name
  end
end

You even can include many instance variables in the same line. Let’s say the student class has another instance variable, for example age.

class Student
  attr_reader :name, :age #this replaces the getter method above
  
  def initialize(name, age)
    @name = name
    @age = age
  end
end

Macro for setter method

class Student
  attr_writer :name, :age #this replaces the setter method bellow
  def initialize(name, age)
    @name = name
    @age = age
  end

  #No need for this anymore
  #def name=(name)
  #  @name = name
  #end
end

attr_reader is a macro for getter methods and attr_writer is a macro for setter methods. In some cases, you will need getter and setter methods for the same instance variable. That’s why there is another macro to do both at the same time. attr_accessor is a macro for generating a getter and a setter method.

Macro for both

class Student
  attr_accessor :name, :age
  def initialize(name, age)
    @name = name
    @age = age
  end
end

There is much more than setter and getter macros in Ruby. For example, when declaring a “has many” relationship in Rails application, you would use has_many macro. You can read more about it here.

Hope that helps you understand what macros are in Ruby programming. If you have anything you would like to add, please comment below!