Method_added hook in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the method_added hook in Ruby?

It is a special method called automatically whenever a new instance method is added to a class or module.

beginner

How do you define a method_added hook in a Ruby class?

Define a class method named <code>self.method_added(method_name)</code> inside the class or module.

beginner

What argument does the method_added hook receive?

It receives the name of the method (as a symbol) that was just added.

intermediate

Can method_added be used to modify methods after they are defined?

Yes, it can be used to wrap or change methods right after they are added, for example to add logging or validation.

advanced

What happens if you define a method inside method_added itself?

It triggers method_added again, which can cause infinite recursion unless carefully handled.

What does the method_added hook detect in Ruby?

A When a new instance method is defined

B When a class is created

C When a variable is assigned

D When a module is included

The method_added hook is called whenever a new instance method is added to a class or module.

How do you prevent infinite recursion inside method_added?

A Rename the method being added

B Avoid defining methods inside <code>method_added</code>

C Call <code>super</code> inside <code>method_added</code>

D Use a guard variable to skip re-entry

Using a guard variable to track if method_added is already running prevents infinite recursion.

What type of argument does method_added receive?

A Method body as a string

B Method name as a symbol

C Class name as a string

D No arguments

method_added receives the name of the method just added as a symbol.

Where should method_added be defined to work properly?

A Inside the class or module as a class method

B Outside any class or module

C Inside an instance method

D Inside a block passed to <code>define_method</code>

method_added must be defined as a class method inside the class or module.

Which of these is a common use of method_added?

A Creating new classes

B Deleting methods from a class

C Automatically wrapping new methods with extra behavior

D Changing variable values

method_added is often used to wrap or modify methods right after they are defined.

Explain how the method_added hook works and give an example of when you might use it.

Think about how Ruby tells you when a new method appears.

Describe a potential problem when defining methods inside method_added and how to avoid it.

What happens if the hook triggers itself repeatedly?