Method_missing for catch-all in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is method_missing in Ruby?

method_missing is a special Ruby method that catches calls to methods that don't exist on an object. It lets you handle or respond to those calls dynamically.

beginner

How do you define method_missing in a Ruby class?

You define method_missing by creating a method named method_missing that takes at least one argument (the method name) and optionally others (arguments and block). Example:<br>def method_missing(name, *args, &block)

intermediate

Why use method_missing for catch-all methods?

It lets you catch any call to undefined methods and handle them in one place. This is useful for dynamic behavior, like delegating calls or creating flexible APIs.

intermediate

What should you do inside method_missing to avoid breaking Ruby's method lookup?

You should call super if you don't handle the method yourself. This lets Ruby raise the usual NoMethodError if needed.

beginner

How can method_missing improve user experience in a Ruby program?

It can provide helpful error messages or fallback behavior when users call methods that don't exist, making the program more forgiving and flexible.

What does method_missing do in Ruby?

A Prevents method calls

B Defines new methods automatically

C Handles calls to undefined methods

D Deletes methods from a class

method_missing catches calls to methods that don't exist and lets you handle them.

Which argument does method_missing always receive?

A The method's source code

B The method's return value

C The class name

D The method name as a symbol

The first argument to method_missing is the name of the missing method as a symbol.

What should you do inside method_missing if you don't handle a method call?

A Call <code>super</code>

B Return nil

C Raise a custom error

D Ignore the call

Calling super passes the call up so Ruby can raise NoMethodError properly.

Which of these is a common use of method_missing?

A Creating dynamic method handlers

B Improving performance by caching

C Encrypting method names

D Automatically documenting methods

method_missing is often used to create dynamic methods or delegate calls.

What happens if you don't define method_missing and call an undefined method?

A The method is created automatically

B Ruby raises <code>NoMethodError</code>

C The program crashes silently

D The call is ignored

Ruby raises a NoMethodError when a method is missing and method_missing is not defined.

Explain how method_missing works in Ruby and why it is useful.

Think about how Ruby handles unknown method calls.

Describe a simple example where method_missing can be used to create flexible method calls.

Imagine a class that responds to any method starting with 'say_'.