return value method callback

result_callback.rb

class Result

  def self.success
    Result.new
  end

  def self.error(error)
    Result.new(error)
  end

  def initialize(error = nil)
    @error = error
  end

  def on_success
    yield unless @error
  end

  def on_error
    yield(@error) if @error
  end
end

def method_that_computes_something
  # do some stuff
  #yield Result.error("bwaahh")
  yield Result.success
end


def main
  method_that_computes_something do |status|
    status.on_success do
      puts 'success'
    end

    status.on_error do |error|
      puts "error: #{error}"
    end
  end
end

main()