03 functions

View the source code.

File

ruby functions.rb

Interpreter

$irb
irb(main):001:0> def greeting
irb(main):002:1> puts "Hello"
irb(main):003:1> end
=> nil
irb(main):004:0> greeting
Hello
=> nil

Demonstrates how to define functions and call them.

Some people say Ruby has no functions, only methods. Others use function to mean the kind of methods we define in this program.

def greeting
  puts "Hello Steve"
end

We say these methods are defined at top-level. Methods defined at top-level become private instance methods of the Object class. Here, top-level is behaving like a class, not an instance of a class.

method(:greeting).owner #=> Object
Object.private_method_defined(:greeting) #=> true

For a discussion of how top-level sometimes behaves like an object and sometimes behaves like a class, see What is the Ruby Top-Level?.