Custom modules as mixins in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a mixin in Ruby?

A mixin is a module that you include in a class to add reusable methods without using inheritance.

beginner

How do you include a custom module as a mixin in a Ruby class?

Use the <code>include</code> keyword inside the class to add the module's methods as instance methods.

intermediate

What is the difference between include and extend when using modules?

<code>include</code> adds module methods as instance methods; <code>extend</code> adds them as class methods.

beginner

Can a Ruby class include multiple modules as mixins?

Yes, a class can include many modules to combine different sets of methods.

intermediate

Why use custom modules as mixins instead of inheritance?

Mixins let you share behavior across unrelated classes without forcing a strict parent-child relationship.

How do you add a module's methods as instance methods in a Ruby class?

A Using <code>import</code>

B Using <code>extend</code>

C Using <code>inherit</code>

D Using <code>include</code>

Use include to add module methods as instance methods.

What keyword adds module methods as class methods to a Ruby class?

A extend

B mix

C include

D use

extend adds module methods as class methods.

Which of these is true about Ruby modules used as mixins?

A They allow multiple inheritance.

B They only work with subclasses.

C They let you share methods across classes.

D They replace classes.

Modules let you share methods across different classes without inheritance.

Can a Ruby class include more than one module?

A No, only one module is allowed.

B Yes, multiple modules can be included.

C Only if they are related modules.

D Only if they are in the same file.

Ruby classes can include many modules to combine behaviors.

Why might you use a module as a mixin instead of inheritance?

A To share behavior without a parent-child relationship.

B To avoid code reuse.

C To make classes unrelated.

D To prevent method overriding.

Mixins share behavior across classes without forcing inheritance.

Explain how to create and use a custom module as a mixin in Ruby.

Think about how you add shared behavior to different classes.

Describe the difference between include and extend when using modules in Ruby.

Consider who can call the methods after adding the module.