Question

A bit confused about Ruby’s initialize method.

Why does not it return my value, as other methods do?

class SomeClass

  attr_reader :val

  def initialize a, b, c
    @val = a + b + c
    @val
  end

end

val = SomeClass.new 1, 2, 3

I need val to be 6 not initialized object.

Of course i can use val.val but that’s another story.

Answer 1

You need to override self.new method:

class SomeClass
  def self.new(*)
    instance = super
    instance.val
  end

  attr_reader :val

  def initialize a, b, c
    @val = a + b + c
    @val
  end

end

p SomeClass.new 1, 2, 3
#=> 6

When you create a instance of a class you are in fact calling self.new of that class which then call initialize method and return the initialized instance.

See live demo here