Why Block parameters in Ruby? - Purpose & Use Cases

The Big Idea

What if you could write one method that does many jobs just by changing a tiny piece of code you pass in?

The Scenario

Imagine you want to repeat a task several times, but each time you need to do something slightly different with the data. Without block parameters, you might write the same loop again and again, changing bits manually.

The Problem

This manual way is slow and boring. You risk making mistakes copying and changing code. It's hard to keep track of what changes where, and fixing bugs becomes a headache.

The Solution

Block parameters let you pass little pieces of code (blocks) that can take inputs and run inside a method. This means you write the loop once, and customize what happens inside by giving it different blocks with parameters. It's clean, flexible, and easy to read.

Before vs After

✗ Before

numbers.each do |n|
  puts n * 2
end

numbers.each do |n|
  puts n + 3
end

✓ After

def repeat_action(numbers)
  numbers.each do |n|
    yield(n)
  end
end

repeat_action(numbers) { |x| puts x * 2 }
repeat_action(numbers) { |x| puts x + 3 }

What It Enables

Block parameters let you write flexible methods that can do many different things with the same data, just by changing the block you pass in.

Real Life Example

Think about a recipe where you always bake cookies but sometimes add chocolate chips, sometimes nuts. Block parameters let you keep the baking steps the same and just change the extra ingredient easily.

Key Takeaways

Manual repetition is slow and error-prone.

Block parameters let methods accept custom code with inputs.

This makes your code cleaner, reusable, and easier to change.