Class.new for dynamic class creation in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does Class.new do in Ruby?

<p><code>Class.new</code> creates a new class dynamically at runtime instead of defining it with the <code>class</code> keyword.</p>

beginner

How can you add methods to a class created with <code>Class.new</code>?

<p>You can pass a block to <code>Class.new</code> and define methods inside that block, just like inside a normal class definition.</p>

intermediate

What is the difference between Class.new and the usual class keyword?

<p><code>Class.new</code> creates a class object dynamically and returns it, while <code>class</code> defines a class with a fixed name in the code.</p>

beginner

How do you create an instance of a class created with <code>Class.new</code>?

Assign the result of Class.new to a variable, then call .new on that variable to create an instance.

intermediate

Can <code>Class.new</code> take a superclass as an argument? If yes, how?

<p>Yes. You can pass a superclass as an argument to <code>Class.new</code> like <code>Class.new(Superclass)</code> to create a subclass dynamically.</p>

What does Class.new return in Ruby?

A A new class object

B An instance of a class

C A string with class name

D A method definition

Class.new returns a new class object that you can assign to a variable or constant.

How do you define methods inside a class created with Class.new?

A By calling <code>def</code> outside the block

B By passing a block to <code>Class.new</code> and defining methods inside it

C By using <code>module</code> keyword

D You cannot define methods dynamically

Methods can be defined inside the block passed to Class.new, just like inside a normal class.

Which of the following is a correct way to create a subclass dynamically?

A Class.new()

B Subclass.new(Superclass)

C class Subclass < Superclass end

D Class.new(Superclass)

Passing a superclass to Class.new creates a subclass dynamically.

How do you create an instance of a class created with klass = Class.new?

A klass.new

B new klass()

C Class.new.new

D klass.create()

Call .new on the class object stored in klass to create an instance.

What is a practical use of Class.new?

A Defining global variables

B Replacing all class definitions

C Creating classes on the fly when you don’t know the name beforehand

D Creating modules

Class.new is useful for dynamic class creation when class names or behavior depend on runtime data.

Explain how Class.new can be used to create a class dynamically and add methods to it.

Think about how you define a normal class and how that translates to using Class.new

Describe how inheritance works with Class.new when creating subclasses dynamically.

Consider how you normally write <code>class Subclass < Superclass</code> and how Class.new can do the same