Method_missing for catch-all in Ruby - Mini Project: Build & Apply

Using method_missing for catch-all in Ruby

📖 Scenario: Imagine you are building a simple Ruby class that can respond to any method call by printing a message. This is useful when you want to catch all undefined method calls and handle them gracefully.

🎯 Goal: You will create a Ruby class that uses method_missing to catch all calls to undefined methods and print a message showing the method name and arguments.

📋 What You'll Learn

Create a class called CatchAll

Define a method_missing method inside the class

Make method_missing print the method name and any arguments passed

Create an instance of CatchAll and call an undefined method on it

Print the output of the undefined method call

💡 Why This Matters

🌍 Real World

Using <code>method_missing</code> helps create flexible Ruby classes that can handle unexpected method calls without errors, useful in dynamic APIs or proxy objects.

💼 Career

Understanding <code>method_missing</code> is important for Ruby developers working with metaprogramming, dynamic method handling, and building DSLs (domain-specific languages).

1

Create the CatchAll class

Create a class called CatchAll with no methods inside.

Ruby

class CatchAll
  # Your code here
end

Need a hint?

Use the class keyword followed by CatchAll and end.

2

Add method_missing to catch undefined methods

Inside the CatchAll class, define a method called method_missing that takes two parameters: method_name and *args.

Ruby

class CatchAll
  def method_missing(method_name, *args)
    # Your code here
  end
end

Need a hint?

Define def method_missing(method_name, *args) inside the class.

3

Print method name and arguments inside method_missing

Inside method_missing, write a puts statement that prints: "Called method: with arguments: " using string interpolation.

Ruby

class CatchAll
  def method_missing(method_name, *args)
    # Your code here
  end
end

Need a hint?

Use puts with double quotes and #{} to insert variables. Use args.inspect to print arguments as an array.

4

Create instance and call undefined method

Create an instance called obj of CatchAll and call the undefined method hello with arguments "world" and 123. This should print the catch-all message.

Ruby

class CatchAll
  def method_missing(method_name, *args)
    puts "Called method: #{method_name} with arguments: #{args.inspect}"
  end
end

# Your code here

Need a hint?

Create obj = CatchAll.new and call obj.hello("world", 123).