Include for instance methods in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the include keyword do in Ruby?

It adds the methods from a module as instance methods to a class, so objects of that class can use those methods.

beginner

How do instance methods from a module become available in a Ruby class?

By using include ModuleName inside the class, the module's instance methods become instance methods of the class.

beginner

Given this module:<br>

module Greet
  def hello
    "Hi!"
  end
end

<br>How do you make hello available to instances of class Person?

Inside the Person class, write include Greet. Then any Person object can call hello.

intermediate

What is the difference between include and extend in Ruby?

<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 for instance methods?

Yes, a class can include many modules. All their instance methods become available to the class's objects.

What happens when you use include with a module in a Ruby class?

A The module is copied as a subclass.

B The module's methods become class methods of the class.

C Nothing happens automatically.

D The module's methods become instance methods of the class.

Using include adds the module's methods as instance methods to the class.

Which keyword adds module methods as class methods instead of instance methods?

A extend

B include

C require

D import

extend adds module methods as class methods.

If a module has a method greet, how do you call it on an object of a class that included the module?

A object.greet

B ClassName.greet

C ModuleName.greet

D You cannot call it

Instance methods from included modules are called on objects.

Can a Ruby class include more than one module to get instance methods?

A No, only one module can be included.

B Yes, multiple modules can be included.

C Only if modules are nested.

D Only if modules have different names.

Ruby classes can include many modules to get their instance methods.

What is the effect of including a module inside a Ruby class?

A It creates a new subclass.

B It copies the module's code into the class.

C It adds the module's instance methods to the class.

D It deletes existing methods in the class.

Including a module adds its instance methods to the class.

Explain how the include keyword works to add instance methods from a module to a Ruby class.

Think about how a class gets new methods from a module.

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

One affects objects, the other affects the class itself.