Method overriding in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of overridden method in subclass

What is the output of the following Ruby code?

Ruby

class Animal
  def speak
    "Hello from Animal"
  end
end

class Dog < Animal
  def speak
    "Woof!"
  end
end

puts Dog.new.speak

A Hello from Animal

B RuntimeError

C nil

D Woof!

💡 Hint

The subclass method with the same name replaces the parent method.

The Dog class overrides the speak method from Animal. So calling speak on Dog instance returns "Woof!".

❓ Predict Output

intermediate

Calling super in overridden method

What will this Ruby code print?

Ruby

class Parent
  def greet
    "Hi"
  end
end

class Child < Parent
  def greet
    super + ", there!"
  end
end

puts Child.new.greet

A there!

B Hi, there!

C Hi

D NoMethodError

💡 Hint

super calls the parent method's version.

The Child's greet method calls super to get "Hi" from Parent, then adds ", there!".

❓ Predict Output

advanced

Overriding method with different parameters

What is the output of this Ruby code?

Ruby

class Base
  def info(x)
    "Base: #{x}"
  end
end

class Derived < Base
  def info(x, y = nil)
    if y
      "Derived: #{x} and #{y}"
    else
      super(x)
    end
  end
end

puts Derived.new.info(5)
puts Derived.new.info(5, 10)

A

Base: 5
Derived: 5 and 10

B

Derived: 5
Derived: 5 and 10

C ArgumentError

D

Base: 5
Base: 5

💡 Hint

The overridden method uses default parameter and calls super conditionally.

When called with one argument, Derived calls super with that argument, printing "Base: 5". With two arguments, it prints "Derived: 5 and 10".

❓ Predict Output

advanced

Effect of overriding method without calling super

What will this Ruby code output?

Ruby

class Vehicle
  def description
    "Vehicle base description"
  end
end

class Car < Vehicle
  def description
    "Car specific description"
  end
end

puts Vehicle.new.description
puts Car.new.description

A

Vehicle base description
Car specific description

B

Vehicle base description
Vehicle base description

C

Car specific description
Car specific description

D NoMethodError

💡 Hint

Overriding replaces the parent method unless super is called.

Vehicle's description prints its own string. Car overrides description and prints its own string, ignoring Vehicle's.

🧠 Conceptual

expert

Understanding method lookup with overriding and modules

Given this Ruby code, what is the output?

Ruby

module M
  def greet
    "Hello from M"
  end
end

class A
  def greet
    "Hello from A"
  end
end

class B < A
  include M
  def greet
    super + " and B"
  end
end

puts B.new.greet

A NoMethodError

B Hello from A and B

C Hello from M and B

D Hello from B

💡 Hint

Modules included in a class come before the superclass in method lookup.

B includes module M, so M's greet is found before A's. B's greet calls super, which calls M's greet, then adds " and B".