resque's wacky failure backend architecture

base.rb

module Resque
  module Failure
    class Base
    end
  end
end

failure.rb

module Resque
  module Failure
    @backend = nil

                                                                                                                                      
    #                                                                                                                                 
    # Sets the current backend. Expects a class descendant of                                                                         
    # `Resque::Failure::Base`.                                                                                                        
    #                                                                                                                                 
    # Example use:                                                                                                                    
    #   require 'resque/failure/hoptoad'                                                                                              
    #   Resque::Failure.backend = Resque::Failure::Hoptoad                                                                            
    def self.backend=(backend)                                                                                                        
      @backend = backend                                                                                                              
    end                                                                                                                               
                                                                                                                                      
    # Returns the current backend class. If none has been set, falls                                                                  
    # back to `Resque::Failure::Redis`                                                                                                
    def self.backend                                                                                                                  
      @backend ||= begin                                                                                                              
        require 'resque/failure/redis'                                                                                                
        Failure::Redis                                                                                                                
      end                                                                                                                             
    end      

    def self.remove(id)                                                                                                               
      backend.remove(id)                                                                                                              
    end                                                                                                                               
  end
end

redis_multi_queue.rb

module Resque                                                                                                                         
  module Failure                                                                                                                      
    # A Failure backend that stores exceptions in Redis. Very simple but                                                              
    # works out of the box, along with support in the Resque web app.                                                                 
    class RedisMultiQueue < Base                                                                                                      
  
      def self.remove(id, queue = :failed)                                                                                            
        sentinel = ""                                                                                                                 
        Resque.redis.lset(queue, id, sentinel)                                                                                        
        Resque.redis.lrem(queue, 1,  sentinel)                                                                                        
      end   
  end
end