Rescue modifier (inline form) in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the rescue modifier (inline form) in Ruby?

It is a way to handle exceptions in a single line using the rescue keyword after an expression. It returns the expression's value if no error occurs, or the rescue value if an error happens.

beginner

How does the rescue modifier differ from a full begin-rescue-end block?

The rescue modifier is shorter and used inline after an expression, while begin-rescue-end is a block that can handle multiple lines and more complex error handling.

beginner

Example: What does result = 10 / 0 rescue 'error' return?

It returns the string 'error' because dividing by zero raises an exception, which is caught by the rescue modifier.

intermediate

Can the rescue modifier catch specific exception types?

No, the rescue modifier catches all StandardError exceptions by default. For specific exceptions, use a full begin-rescue block.

beginner

Why use the rescue modifier instead of a full rescue block?

It makes code shorter and cleaner for simple error handling when you want to provide a fallback value quickly.

What does the rescue modifier do in Ruby?

A Handles exceptions inline and returns a fallback value if an error occurs

B Defines a new method

C Creates a loop

D Declares a variable

The rescue modifier catches exceptions inline and returns the fallback value if an error happens.

Which of these is a correct use of the rescue modifier?

A rescue value = 5 / 0 'fail'

B value = 5 / 0 rescue 'fail'

C begin value = 5 / 0 rescue 'fail' end

D value = rescue 5 / 0 'fail'

The rescue modifier is used after an expression, like value = 5 / 0 rescue 'fail'.

If no error occurs, what does the rescue modifier return?

A The original expression's value

B The rescue value

C nil

D An error message

If no error happens, the rescue modifier returns the original expression's value.

Can the rescue modifier specify which exception to catch?

A No, it catches all exceptions including system errors

B Yes, by adding the exception name after rescue

C Yes, by using a block

D No, it catches all StandardError exceptions

The rescue modifier catches all StandardError exceptions by default; specific exceptions require a full rescue block.

Which is a benefit of using the rescue modifier?

A Handles multiple exceptions separately

B Allows retrying the code automatically

C Shorter code for simple error handling

D Logs errors to a file

The rescue modifier makes code shorter and cleaner for simple fallback values.

Explain how the rescue modifier works in Ruby and when you might use it.

Think about how to handle errors quickly in one line.

Write a Ruby expression using the rescue modifier to divide two numbers and return 'error' if division fails.

Use the rescue keyword after the division.