gistfile1.txt

class TwitterWelcomeMessageService
  def self.call(*args)
    new(*args).call
  end
  
  private
  
  def call(twitter_handle)
    client.update("@#{twitter_handle} welcome to 'Oranges & Apples', we hope you enjoy our juicy fruit!")
  end
  
  def client
    @client ||= Twitter::REST::Client.new do |config|
      config.consumer_key        = "..."
      config.consumer_secret     = "..."
      config.access_token        = "..."
      config.access_token_secret = "..."
    end
  end
end

class UsersController
  def create
    # ...
    TwitterWelcomeMessageService.call(user.twitter_handle)
  end
end