Is it possible to implement the same functionality with a class as in a module?

In Ruby, modules (module) and classes (class) have different purposes, although both can contain methods and constants.

• Modules are intended for grouping methods, constants, and other modules without the ability to create instances. They are often used for mixins (including functionality in classes via include or extend).

• Classes allow creating objects (instances), have constructors, and can be inherited.

You can implement module functionality within a class, but this means that to access the methods, you need to create an instance of the class, which is not always convenient or logical. Modules, on the other hand, allow adding methods directly to the namespace or class without creating an object.

Example:

module Greetings
  def greet
    puts "Hello!"
  end
end

class Person
  include Greetings
end

Person.new.greet # => Hello!

If you try to replace a module with a class, then to call greet, you need to create an object:

class Greetings
  def greet
    puts "Hello!"
  end
end

g = Greetings.new
g.greet # => Hello!

Thus, although technically possible, using modules for mixins and grouping methods is more semantically correct and convenient.