Ruby modules are powerful tools for organizing and sharing code. They serve as containers for methods, constants, and classes, promoting code reusability and maintainability.

Defining a Module

To create a module in Ruby, use the module keyword followed by the module name in CamelCase:


module MyModule
  # Module contents go here
end

Adding Methods to a Module

You can define methods within a module just like you would in a class:


module Greeting
  def say_hello(name)
    puts "Hello, #{name}!"
  end
end

Module Constants

Modules can also contain constants, which are useful for storing configuration values or other fixed data:


module MathConstants
  PI = 3.14159
  E = 2.71828
end

Namespacing with Modules

Modules are excellent for Ruby Namespaces, helping to avoid naming conflicts:


module Animals
  class Dog
    def speak
      puts "Woof!"
    end
  end
end

Animals::Dog.new.speak  # Output: Woof!

Module Inclusion

To use module methods as instance methods in a class, include the module:


class Person
  include Greeting
end

person = Person.new
person.say_hello("Alice")  # Output: Hello, Alice!

For more details on including modules, see Ruby Module Inclusion.

Best Practices for Module Creation

Use modules for grouping related functionality
Keep module names descriptive and concise
Avoid creating modules with too many responsibilities
Use modules to implement mixins for sharing behavior across classes
Consider using modules for utility functions that don't require state

Common Use Cases

Modules in Ruby are frequently used for:

Organizing related methods and constants
Implementing mixins to share behavior
Creating namespaces to avoid naming conflicts
Extending core Ruby classes with new functionality

Conclusion

Ruby module creation is a fundamental concept for organizing and structuring code. By mastering module creation, you'll be able to write more maintainable and reusable Ruby code. For more advanced topics, explore Ruby Mixins and Ruby Metaprogramming.