mulligan - a concept for dealing with things that can fail frequently

example.rb

Mulligan.initialize

puts "BEGIN"

#succeeding
mulligan(:times => 4) do
  puts "mulligan!"

end.on_failure do
  puts "fail"
end.on_success do
  puts "winning"
end

#failing
mulligan(:times => 4) do
  puts "mulligan!"

  raise

end.on_failure do
  puts "fail"
end.on_success do
  puts "winning"
end

puts "DONE"

mulligan.rb

module Mulligan
  class MulliganResult

    attr_accessor :success

    def initialize(options)
      self.success = options[:success]
    end

    def on_failure(&block)
      if !success
        block.call
      end

      self
    end

    def on_success(&block)
      if success
        block.call
      end

      self
    end

  end

  module InstanceMethods
    def mulligan(options, &block)
      times_to_run = options.delete(:times) || 1
      wait_time = options.delete(:wait_time) || 0.5

      times_to_run.times do
        begin 
          block.call
          @success = true
          break
        rescue => e
          sleep wait_time
          @success = false
        end
      end

      ::Mulligan::MulliganResult.new(:success => @success)
    end
  end

  def self.initialize
    Object.send(:include, Mulligan::InstanceMethods)
  end

end

practical_example.rb

# A Rails controller action
def update_twitter 
  mulligan(:times => 4) do
    @tweet = current_visitor.twitter_client.update(params[:msg])

  end.on_failure do
    flash[:error] = 'Could not post tweet'

  end.on_success do
    Conversation.create! :tweet => @tweet
    redirect_to dashboard_path
  end
end