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Ruby Mixins

Here, we are going to learn about the Mixins in Ruby programming with examples.
Submitted by Hrithik Chandra Prasad, on November 11, 2020

Before reading this article on mixins, you should be very well aware of the things related to Object-Oriented programming and in that, particularly Inheritance.

We all know that Ruby does not support multiple inheritances directly which means a child class cannot have more than one parent class. This simply means that it can only inherit the features of a single parent class. When we have to make a child class to inherit the features of more than one Base class, then we take help from Mixins. Mixins can also be considered as the mechanism to implement indirect multiple Inheritances. We use the method include to implement mixins and there is no restriction on the number of mixins a class may have. Let us understand mixins with the help of syntax and demonstrating program codes.

Syntax:

class M1
    Include M2
    Include M3
end

Example 1:

=begin	
Program to demonstrate Mixins	
=end

module Printhello
    def prnt1
        puts "Hello"
    end
    
    def prnt2
        puts "Hi"
    end
end

module Printbye
    def prnt3
        puts "Bye"
    end
    def prnt4
        puts "Take Care"
    end
end

class Includehelp
    include Printhello
    include Printbye
    def Add
        puts "Follow Includehelp on Instagram"
    end
end

obj1 = Includehelp.new
obj1.prnt1
obj1.prnt2
obj1.prnt3
obj1.prnt4
obj1.Add

Output:

Hello
Hi
Bye
Take Care
Follow Includehelp on Instagram

Explanation:

In the above code, you can observe that we are implementing mixins as well as multiple inheritances in Ruby indirectly. The class Includehelp has two modules now, namely, Printhello and Printbye. The child class is now able to access all the methods or features of all the two base classes. This is how you can make a class multiply inherited in Ruby.

Example 2:

=begin	
Program to demonstrate Mixins	
=end 
module Parent_1 
    def a1 
        puts 'This is Parent one.'
    end
end

module Parent_2 
    def a2 
        puts 'This is Parent two.'
    end
end

module Parent_3 
    def a3 
        puts 'This is Parent three.'
    end
end

class Child 
    include Parent_1 
    include Parent_2 
    include Parent_3 
    def display 
        puts 'Three modules have been included.'
    end
end 

object = Child.new
object.display 
object.a1 
object.a2 
object.a3

Output:

Three modules have been included.
This is Parent one.
This is Parent two.
This is Parent three.

Explanation:

In the above code, you can observe that we are implementing mixins as well as multiple inheritances in Ruby indirectly. The class child has three modules now, namely, Parent_1, Parent_2, and Parent_3. The child class is now able to access all the methods or features of all the three base classes.