Module to initialize required attributes

init_attributes.rb

module InitAttributes
  def self.included(base)
    base.send(:include, InstanceMethods)
    base.extend(ClassMethods)
  end

  module InstanceMethods
    def initialize(attributes)
      init_instance_variables(self.class.accessor_attributes, attributes)
      init_instance_variables(self.class.reader_attributes,   attributes)
    end

    private

    def init_instance_variables(required_attributes, given_attributes)
      required_attributes.each do |attr|
        instance_variable_set("@#{attr}", given_attributes.fetch(attr))
      end
    end
  end

  module ClassMethods
    def accessor_attributes
      @accessor_attributes ||= []
    end

    def reader_attributes
      @reader_attributes ||= []
    end

    private

    def init_attr_accessor(*attributes)
      attr_accessor(*attributes)
      @accessor_attributes = attributes
    end

    def init_attr_reader(*attributes)
      attr_reader(*attributes)
      @reader_attributes = attributes
    end
  end
end

class Akira
  include InitAttributes

  init_attr_reader   :one
  init_attr_accessor :two

  def do_something
    puts 'Doing something...'
  end
end

ls Akira
# InitAttributes::ClassMethods#methods: accessor_attributes  reader_attributes
# Akira#methods: do_something  one  two  two=
# instance variables: @accessor_attributes  @reader_attributes

akira = Akira.new(one: 1, two: 2)
# => #<Akira:0x007ff1da152e48 @one=1, @two=2>

ls akira
# Akira#methods: do_something  one  two  two=
# instance variables: @one  @two

Akira.new(one: 1)
# => KeyError: key not found: :two