Question

In Ruby, what is the difference between putting code in an initialize() method rather than directly in the class body? Both appear to be executed when calling MyClass.new.

Clearly, initialize() can accept parameters, but is that the only difference?

class MyClass
  puts 'Hello'

  def initialize(params)
    puts 'World'
  end
end

Answer 1

Try to create two instances of MyClass

a = MyClass.new
b = MyClass.new

to see the difference:

Hello

World

World

Code in the class body execute only once – when ruby loads the file. initialize() executes every time you create a new instance of your class.