Question

I know self is the receiver of the method calling.
But I do not know if there is not self in method definition.

code example:

class One
  def kk
    "kk"
  end
  def self.kkk
    "kkk"
  end
end

puts One.new.kk
puts One.kkk

Why do I need to use new method for One used like One.new.kk ?

Answer 1

self.kkk here defines a class method of One. As you know, self is the receiver. In the context here it is the One class.

And One.new returns an instance of class One. kk is an instance method that only called by an instance.