Why Include for instance methods in Ruby? - Purpose & Use Cases

The Big Idea

What if you could fix a bug once and see it fixed everywhere instantly?

The Scenario

Imagine you have several classes in your Ruby program, and each class needs the same set of methods to work properly. You try to copy and paste these methods into every class manually.

The Problem

This manual copying is slow and boring. If you want to change a method, you have to find and update it in every class separately. This causes mistakes and wastes time.

The Solution

Using include lets you write the methods once in a module and then add them to any class easily. This way, all classes share the same methods, and updating them happens in one place.

Before vs After

✗ Before

class Dog
  def speak
    puts 'Hello!'
  end
end

class Cat
  def speak
    puts 'Hello!'
  end
end

✓ After

module Speakable
  def speak
    puts 'Hello!'
  end
end

class Dog
  include Speakable
end

class Cat
  include Speakable
end

What It Enables

This makes your code cleaner, easier to maintain, and lets you add shared behavior to many classes quickly.

Real Life Example

Think of a game where many characters can jump. Instead of writing jump code in every character class, you put it in a module and include it wherever needed.

Key Takeaways

Copying methods manually is slow and error-prone.

include shares methods across classes easily.

Updating shared methods happens in one place, saving time.