Why class-level behavior matters in Ruby - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a class method in Ruby.

Ruby

class Car
  def self.[1]
    "This is a class method"
  end
end

Drag options to blanks, or click blank then click option'

Ainfo

Bstart

Cdescription

Ddrive

Attempts:

3 left

💡 Hint

Common Mistakes

Using instance method names without self. prefix.

The method name info is used here as a class method example. It can be called on the class itself.

2fill in blank

medium

Complete the code to call the class method correctly.

Ruby

class Dog
  def self.[1]
    "Bark!"
  end
end

puts Dog.[1]

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Asound

Bspeak

Cnoise

Dbark

Attempts:

3 left

💡 Hint

Common Mistakes

Calling class methods on instances instead of the class.

The class method bark is defined and called on the class Dog.

3fill in blank

hard

Fix the error in the code by completing the blank.

Ruby

class Cat
  def [1]
    "Meow"
  end
end

puts Cat.meow

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Aclass.meow

Bmeow

Cself.meow

Ddef.meow

Attempts:

3 left

💡 Hint

Common Mistakes

Defining instance methods but trying to call them on the class.

To define a class method, prefix the method name with self.. Here, def self.meow defines a class method.

4fill in blank

hard

Fill in the blank to create a class method that accesses the class variable.

Ruby

class Book
  @@count = 0

  def self.[1]
    @@count
  end
end

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Acount

Bclass_variable

Cdef

Ddef self.count

Attempts:

3 left

💡 Hint

Common Mistakes

Using instance variables instead of class variables.

Class variables start with @@. The class method count accesses and returns it.

5fill in blank

hard

Fill both blanks to define a class method that increments a class variable and returns it.

Ruby

class Counter
  @@total = 0

  def self.[1]
    @@total [2] 1
  end
end

Drag options to blanks, or click blank then click option'

Aclass_variable

Bincrement

C+=

Ddef

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to use self. for class methods.

Using =+ instead of +=.

Class variables start with @@. Define the class method increment and use += to increment and return the new value.