String freezing for immutability in Ruby - Mini Project: Build & Apply

String freezing for immutability

📖 Scenario: Imagine you are working on a program that uses fixed messages that should never change during the program's run. To protect these messages from accidental changes, you will learn how to make strings immutable by freezing them.

🎯 Goal: You will create a string, freeze it to make it immutable, and then try to modify it to see what happens.

📋 What You'll Learn

Create a string variable with a specific message

Freeze the string to make it immutable

Attempt to modify the frozen string

Observe the error raised when modifying a frozen string

💡 Why This Matters

🌍 Real World

Freezing strings helps protect important fixed messages or configuration values in programs so they cannot be changed by mistake.

💼 Career

Understanding immutability and error handling is important for writing safe and reliable Ruby code in professional software development.

1

Create a string variable

Create a string variable called message and set it to the exact text "Welcome to Ruby!".

Ruby

# Create the string variable 'message' with the text "Welcome to Ruby!"
# Your code here

Need a hint?

Use = to assign the string to the variable message.

2

Freeze the string

Freeze the string message by calling the freeze method on it and reassign the result back to message.

Ruby

message = "Welcome to Ruby!"
# Freeze the string 'message' to make it immutable
# Your code here

Need a hint?

Use message.freeze and assign it back to message.

3

Attempt to modify the frozen string

Try to change the first character of message to 'H' by assigning message[0] = 'H'.

Ruby

message = "Welcome to Ruby!"
message = message.freeze
# Attempt to modify the frozen string
# Your code here

Need a hint?

Use the syntax message[0] = 'H' to try to change the first character.

4

Observe the error when modifying a frozen string

Run the program and observe the error message printed when trying to modify the frozen string message. Use begin and rescue to catch the error and print "Cannot modify frozen string".

Ruby

message = "Welcome to Ruby!"
message = message.freeze
begin
  message[0] = 'H'
rescue => e
  # Print the error message below
  # Your code here
end

Need a hint?

Use begin and rescue to catch the error and puts to print the message.