Minimal service object implementation

interactor.rb

class Interactor
  attr_reader :error

  def self.perform(*args)
    new(*args).tap { |interactor| catch(:fail) { interactor.perform } }
  end

  def success?
    @error.nil?
  end

  def fail!(msg)
    @error = msg
    throw :fail
  end

  def perform
    raise NotImplementedError
  end
end

usage.rb

require 'interactor'

class Double < Interactor
  attr_reader :number # attributes which want to be exposed

  def initialize(number)
    @number = number
  end

  def perform
    fail!("unable to double `#{@number}`") unless @number.respond_to? :*
    @number *= 2
  end
end

double = Double.perform(123)
double.success? # => true
double.number   # => 246

double = Double.perform(:abc)
double.success? # => false
double.error    # => "unable to double `abc`"