Why hooks enable framework building in Ruby - See It in Action

Why hooks enable framework building

📖 Scenario: Imagine you are creating a simple event system in Ruby where different parts of a program can react to certain events. This is like setting up hooks where you can attach your own code to run when something happens.

🎯 Goal: You will build a basic event hook system that allows registering and running hooks. This shows how hooks help frameworks let users add custom behavior easily.

📋 What You'll Learn

Create a hash called hooks to store event names and their attached blocks

Create a method called register_hook that takes an event name and a block, and stores the block in hooks

Create a method called run_hook that takes an event name and runs all blocks attached to that event

Demonstrate registering two hooks for the event :start and then running them

💡 Why This Matters

🌍 Real World

Many frameworks use hooks to let users add their own code at key points, like when a web request starts or finishes.

💼 Career

Understanding hooks helps you build or use frameworks that are flexible and customizable, a key skill in software development.

1

Create the hooks storage

Create a hash called hooks and set it to an empty hash {}.

Ruby

# Create a hash called hooks to store event hooks
# Your code here

Need a hint?

Use hooks = {} to create an empty hash.

2

Create the register_hook method

Create a method called register_hook that takes two parameters: event and a block. Inside the method, add the block to the hooks hash under the key event. Initialize the key with an empty array if it does not exist.

Ruby

hooks = {}
# Define register_hook method to add blocks to hooks
# Your code here

Need a hint?

Use hooks[event] ||= [] to create an array if needed, then add the block with << block.

3

Create the run_hook method

Create a method called run_hook that takes one parameter event. Inside the method, check if hooks[event] exists, then call each block stored there using call.

Ruby

hooks = {}
def register_hook(event, &block)
  hooks[event] ||= []
  hooks[event] << block
end
# Define run_hook method to run all blocks for an event
# Your code here

Need a hint?

Use hooks[event].each { |hook| hook.call } to run each block.

4

Register and run hooks

Register two hooks for the event :start using register_hook. The first hook should print "First start hook" and the second should print "Second start hook". Then call run_hook(:start) to run them.

Ruby

hooks = {}
def register_hook(event, &block)
  hooks[event] ||= []
  hooks[event] << block
end
def run_hook(event)
  if hooks[event]
    hooks[event].each { |hook| hook.call }
  end
end
# Register two hooks for :start and run them
# Your code here

Need a hint?

Use register_hook(:start) { puts "First start hook" } and similar for the second hook, then run_hook(:start).