Default Parameter Values

In this lesson you will learn how to give a Ruby parameter a default value so callers can leave it out. This is for anyone searching for "Ruby default parameter how to use".

Writing = value on a parameter sets a default that is used automatically when the caller omits that argument. Picture an order form where leaving a field blank gets you the usual house set.

The sample code defines def greet(name = "Guest"), so greet("Alice") uses the value passed while greet falls back to the default "Guest".

A common stumbling block for beginners is that Ruby lets you omit the parentheses on a method call. greet alone calls the method, but until you are used to that shorthand it can be hard to tell a variable from a method call.

Letting callers omit arguments gives you a flexible method that serves both the simple case and the finely tuned one. In practice it is a favourite technique for methods with optional settings.

📖 Reference code

def greet(name = "Guest")
  puts "Hello, #{name}!"
end

greet("Alice")
greet

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