Name reusable work

Learn

Define a method with def, a name, optional parameters in parentheses, a body and end. Calling the method runs the body. Arguments supplied at the call fill the corresponding parameters.

A method returns the value of the last expression it evaluates. Assign that value or pass it to another method such as puts. Printing inside a method and returning a value are separate actions.

Use return value to finish a method early. A parameter may have a default, such as quantity = 1, which is used when that argument is omitted. Local variables created inside a method stay local to that call.

Example

def item_total(price, quantity)
  price * quantity
end

total = item_total(6, 3)
puts total

Experiment

• Try Price two orders

  Predict both totals. Add a third call for 5 items priced at 4 each without changing the definition.

• Try Offer a default quantity

  Predict the two prices. Change the default quantity to 2 and identify which call is affected.

• Try Handle an invalid quantity

  Predict both labels. Change the invalid quantity to 1 and trace which return path runs.

Explore the official manual

• Official Ruby 3.3 documentation: Methods
• Official Ruby 3.3 documentation: Calling Methods