Accessing parent methods in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of calling super in overridden method

What is the output of this Ruby code when Child.new.greet is called?

Ruby

class Parent
  def greet
    "Hello from Parent"
  end
end

class Child < Parent
  def greet
    super + " and Child"
  end
end

puts Child.new.greet

A "Hello from Parent"

B "Hello from Child"

C "Hello from Parent and Child"

D NoMethodError

💡 Hint

Remember that super calls the parent method with the same name.

The greet method in Child calls super, which runs Parent#greet returning "Hello from Parent". Then it adds " and Child" to that string.

❓ Predict Output

intermediate

Calling parent method with arguments

What will be printed when this Ruby code runs?

Ruby

class Parent
  def multiply(x, y)
    x * y
  end
end

class Child < Parent
  def multiply(x, y)
    super(x, y) + 10
  end
end

puts Child.new.multiply(3, 4)

A 22

B 12

C 34

D ArgumentError

💡 Hint

Check how super passes arguments to the parent method.

The multiply method in Child calls super with arguments 3 and 4, which returns 12. Then it adds 10, resulting in 22.

🔧 Debug

advanced

Identify the error when calling parent method

What error will this Ruby code raise when Child.new.show is called?

Ruby

class Parent
  def show
    "Parent show"
  end
end

class Child < Parent
  def show
    super()
  end
end

Child.new.show

A NoMethodError

B TypeError

C ArgumentError

D No error, returns "Parent show"

💡 Hint

Calling super() with empty parentheses calls the parent method with no arguments.

The parent method show takes no arguments. Calling super() correctly calls it without arguments, so it returns "Parent show" without error.

❓ Predict Output

advanced

Using super with default arguments

What is the output of this Ruby code?

Ruby

class Parent
  def info(name = "Parent")
    "Hello, #{name}"
  end
end

class Child < Parent
  def info(name = "Child")
    super
  end
end

puts Child.new.info

A ArgumentError

B "Hello, Child"

C "Hello, "

D "Hello, Parent"

💡 Hint

When calling super without arguments, Ruby passes the current method's arguments to the parent.

The info method in Child has default argument "Child" and calls super without arguments, so it passes the current method's argument (which defaults to "Child") to Parent#info. Therefore, the output is "Hello, Child".

🧠 Conceptual

expert

Understanding super with blocks

Consider this Ruby code. What will be the output when Child.new.process is called?

Ruby

class Parent
  def process
    yield if block_given?
    "Parent done"
  end
end

class Child < Parent
  def process
    result = super do
      "Block from Child"
    end
    result
  end
end

puts Child.new.process

A "Parent done"

B "Block from Child"

C LocalJumpError

D nil

💡 Hint

Check what yield returns and what process returns.

The process method in Parent yields to the block, but the block's return value is ignored. The method then returns "Parent done". The Child method calls super with a block, captures the return value "Parent done", and returns it.