Exception hierarchy in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to raise a standard error.

Ruby

raise [1], "An error occurred"

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

AStandardError

BException

CRuntimeError

DSyntaxError

Attempts:

3 left

💡 Hint

Common Mistakes

Using Exception directly instead of StandardError.

Using SyntaxError which is for syntax issues.

The StandardError is the default for most errors in Ruby. Using raise StandardError creates a standard error.

2fill in blank

medium

Complete the code to rescue only runtime errors.

Ruby

begin
  # some code
rescue [1] => e
  puts e.message
end

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

ARuntimeError

BStandardError

CException

DNoMethodError

Attempts:

3 left

💡 Hint

Common Mistakes

Using Exception which rescues all exceptions.

Using StandardError which is more general.

To rescue only runtime errors, use rescue RuntimeError. This catches errors of that specific type.

3fill in blank

hard

Fix the error in the code to correctly rescue argument errors.

Ruby

begin
  Integer('abc')
rescue [1] => e
  puts "Error: #{e.message}"
end

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

AStandardError

BArgumentError

CRuntimeError

DTypeError

Attempts:

3 left

💡 Hint

Common Mistakes

Using RuntimeError which does not catch argument errors.

Using TypeError which is different.

The method Integer('abc') raises an ArgumentError when the string is invalid. So rescue ArgumentError to catch it.

4fill in blank

hard

Fill both blanks to create a custom error class inheriting from the correct superclass.

Ruby

class MyError < [1]
  def message
    "Custom error message"
  end
end

raise [2], "Oops!"

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

AStandardError

BException

CMyError

DRuntimeError

Attempts:

3 left

💡 Hint

Common Mistakes

Inheriting from Exception which is too broad.

Raising StandardError instead of the custom error.

Custom errors usually inherit from StandardError. To raise the custom error, use its class name MyError.

5fill in blank

hard

Fill all three blanks to correctly check error class and message.

Ruby

begin
  raise [1], "File not found"
rescue [2] => e
  if e.is_a?([3])
    puts e.message
  end
end

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

ARuntimeError

BStandardError

DArgumentError

Attempts:

3 left

💡 Hint

Common Mistakes

Rescuing ArgumentError which won't catch runtime errors.

Checking for wrong error class in is_a?.

The code raises a RuntimeError, rescues StandardError (which includes runtime errors), and checks if the error is a RuntimeError before printing the message.