Block given? check in Ruby - Mini Project: Build & Apply

Block given? check

📖 Scenario: You are creating a simple Ruby method that behaves differently depending on whether a block is given or not. This is useful when you want to allow extra customization but also have a default behavior.

🎯 Goal: Build a Ruby method called greet that prints a default greeting if no block is given, and uses the block to customize the greeting if a block is provided.

📋 What You'll Learn

Create a method named greet

Use block_given? inside the method to check if a block is passed

Print "Hello, World!" if no block is given

If a block is given, call the block and print its result

💡 Why This Matters

🌍 Real World

Checking if a block is given allows Ruby methods to be flexible and customizable, which is common in libraries and frameworks.

💼 Career

Understanding blocks and <code>block_given?</code> is essential for Ruby developers, especially when working with Rails or writing reusable code.

1

Define the greet method

Write a method called greet with no parameters.

Ruby

# Define the greet method
# Your code here

Need a hint?

Use def greet to start the method and end to finish it.

2

Check if a block is given

Inside the greet method, use block_given? to check if a block is passed.

Ruby

def greet
  # Use block_given? to check for a block
  # Your code here
end

Need a hint?

Use an if statement with block_given? inside the method.

3

Call the block or print default greeting

Inside the greet method, if a block is given, call the block with yield and print its result. Otherwise, print "Hello, World!".

Ruby

def greet
  if block_given?
    # Call the block and print its result
    # Your code here
  else
    # Print "Hello, World!"
    # Your code here
  end
end

Need a hint?

Use puts yield to call and print the block result, and puts "Hello, World!" for the default.

4

Test the greet method with and without a block

Write two lines: call greet without a block, then call greet with a block that returns "Hi there!". This will show both behaviors.

Ruby

def greet
  if block_given?
    puts yield
  else
    puts "Hello, World!"
  end
end

# Call greet without a block
# Your code here

# Call greet with a block that returns "Hi there!"
# Your code here

Need a hint?

Call greet alone, then call greet { "Hi there!" } to test both cases.