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Modules in Ruby

Ruby modules: Here, we are going to learn about the modules in Ruby programming language with module declaration syntax and examples.
Submitted by Hrithik Chandra Prasad, on September 28, 2019

Ruby Modules

In Ruby, modules are similar to classes but not exactly considered as classes. You cannot instantiate a module, which simply means that you cannot create objects of modules and provide memory to them. Modules are a collection of methods, classes, and constants. Any variable declared inside a module is treated as a constant and its value can never be changed in the future. With the help of modules, you can share the methods between two classes. You only need to include them in the classes and the methods of modules become accessible to the class.

Modules provide great help when you want to make use of the same method in different classes but also wants to escape from redefining them again and again.

Now, let us understand the syntax of the module first which is given below:

    module Module_name
        #code
    end

You are supposed to use "module" keyword to define a module.

Now, to have a better understanding of the concept, let us go through some of its examples which are specified below:

=begin
Ruby program to demonstrate implementation of module.
=end

module Student  
	Const = 100 
	
	def Student.names 
		puts "Your name is not available!"
	end
		
	def Student.address 
		puts "Your address is not available!"
	end
		
	def Student.education 
		puts "Education is not available!"
	end
	
end

puts Student::Const
 
Student.names
Student.address
Student.education  

Output

100
Your name is not available!
Your address is not available!
Education is not available!

You can observe in the above code that we are creating a module named "Student". We have defined multiple methods. To make use of module constant, you will have to use :: operator amid module name and constant.

Now, let us see how we can use a module inside a class or you can say that how to achieve one of the main objectives of the module with the help of an example provided below:

=begin
Ruby program to demonstrate implementation of module.
=end

module Student  
	Const = 100 
	
	def names 
		puts "Your name is not available!"
	end
		
	def address 
		puts "Your address is not available!"
	end
		
	def education 
		puts "Education is not available!"
	end
	
end

class School
	include Student
	def gets
		puts"Welcome to the school!"
	end
end
 obj = School.new
 obj.education
 obj.address
 obj.names
 obj.gets

Output

Education is not available!
Your address is not available!
Your name is not available!
Welcome to the school!

In the above code, you can observe that we are creating a module named as Student. Then we are creating a class named as School. We are including the Student module in the School class with the help of "include" keyword. We have instantiated the School class and then have invoked the methods of objects as well as the methods of a class with the help of that object.