Closures and variable binding in Ruby - Mini Project: Build & Apply

Closures and Variable Binding in Ruby

📖 Scenario: Imagine you are creating a simple greeting card generator. Each card has a personalized message that includes the recipient's name and a special number. You want to create a function that remembers the special number and uses it whenever you greet someone.

🎯 Goal: Build a Ruby program that demonstrates how closures capture variable bindings by creating a greeting function that remembers a special number and uses it to greet different people.

📋 What You'll Learn

Create a variable to hold a special number

Define a closure (lambda) that uses the special number and a name parameter

Change the special number after defining the closure

Call the closure with different names to see how variable binding works

💡 Why This Matters

🌍 Real World

Closures are used in Ruby for callbacks, event handlers, and to create functions that remember state without using global variables.

💼 Career

Understanding closures helps in writing clean, modular Ruby code and is important for roles involving Ruby on Rails or scripting.

1

Create a variable called special_number and set it to 7

Create a variable called special_number and set it to the integer 7.

Ruby

# Create a variable called special_number and set it to 7
# Your code here

Need a hint?

Use = to assign the value 7 to special_number.

2

Define a closure called greet that takes a name parameter and returns a greeting string using special_number

Define a closure called greet using lambda that takes one parameter name and returns the string "Hello, #{name}! Your special number is #{special_number}.".

Ruby

special_number = 7
# Define a lambda called greet that takes name and returns the greeting string
# Your code here

Need a hint?

Use lambda { |name| ... } to create the closure and use string interpolation with #{}.

3

Change special_number to 42 after defining greet

Change the value of special_number to 42 after the greet lambda is defined.

Ruby

special_number = 7
greet = lambda { |name| "Hello, #{name}! Your special number is #{special_number}." }
# Change special_number to 42
# Your code here

Need a hint?

Simply assign 42 to special_number after the lambda definition.

4

Call greet with "Alice" and "Bob" and print the results

Call the greet lambda with the argument "Alice" and print the result. Then call greet with "Bob" and print the result.

Ruby

special_number = 7
greet = lambda { |name| "Hello, #{name}! Your special number is #{special_number}." }
special_number = 42
# Call greet with "Alice" and print
# Call greet with "Bob" and print
# Your code here

Need a hint?

Use puts greet.call("Alice") and puts greet.call("Bob") to print the greetings.