Instantiating Redis from inside a Celluloid::IO actor causes missing constructor error

[orospakr]

I think the name "Redis" may be overridden in the local scope.

Example code:

#!/usr/bin/env ruby

require "redis"
require "celluloid"
require "celluloid/io"
require 'celluloid/redis'

class MyActor
  # comment this out to prevent the error.
  include Celluloid::IO

  def initialize
    @redis = Redis.new(:driver => :celluloid) 

    puts "Success."
  end
end

ma = MyActor.new
sleep

Error produced:

$ bundle exec ./bin/redis_spike.rb
E, [2013-07-19T10:49:33.717153 #26935] ERROR -- : MyActor crashed!
NoMethodError: undefined method `new' for Celluloid::Redis:Module
        ./bin/redis_spike.rb:13:in `initialize'
        /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/calls.rb:25:in `public_send'
        /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/calls.rb:25:in `dispatch'
        /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/calls.rb:67:in `dispatch'
        /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/actor.rb:326:in `block in handle_message'
        /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/tasks.rb:42:in `block in initialize'
        /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/tasks/task_fiber.rb:11:in `block in create'
D, [2013-07-19T10:49:33.718139 #26935] DEBUG -- : Terminating 1 actors...
D, [2013-07-19T10:49:33.718526 #26935] DEBUG -- : Shutdown completed cleanly
./bin/redis_spike.rb:13:in `initialize': undefined method `new' for Celluloid::Redis:Module (NoMethodError)
        from /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/calls.rb:25:in `public_send'
        from /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/calls.rb:25:in `dispatch'
        from /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/calls.rb:67:in `dispatch'
        from /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/actor.rb:326:in `block in handle_message'
        from /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/tasks.rb:42:in `block in initialize'
        from /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/tasks/task_fiber.rb:11:in `block in create'
        from (celluloid):0:in `remote procedure call'
        from /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/calls.rb:95:in `value'
        from /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/proxies/sync_proxy.rb:28:in `method_missing'
        from /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/legacy.rb:14:in `method_missing'
        from /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid/proxies/actor_proxy.rb:25:in `_send_'
        from /home/orospakr/.gem/ruby/2.0.0/gems/celluloid-0.14.1/lib/celluloid.rb:129:in `new'
        from ./bin/redis_spike.rb:19:in `<main>'

Commenting out include Celluloid::IO prevents the error.

Is it unreasonable for me to want to use Celluloid::Redis from inside a Celluloid::IO actor? I would have thought that a Celluloid::IO Actor is just the right place to use Celluloid::Redis from, since it needs the IO reactor.

[orospakr]

Thanks to benlangfield@irc, apparently the trick is to ground the identifier dereference in the global namespace:

@redis = ::Redis.new

Perhaps the README should be updated to reflect such?

[benlangfeld]

Or Celluloid::Redis should be renamed CelluloidRedis to avoid the collision, especially since it's only used to house Celluloid::Redis::VERSION.

[orospakr]

Agreed.

[tarcieri]

Yeah, the namespace collision is annoying :(

[nagius]

I ran into this bug too. It took me a while to figure it.
We should fix either the namespace collision or the documentation with a working example like :

require 'celluloid/current'
require 'celluloid/io'
require 'celluloid/redis'

class MyActor
    include Celluloid::IO

    def initialize
        @redis = ::Redis.new(:driver => :celluloid)
        async.run
    end

    def run
        every(1) { puts "Tick" }

        @redis.subscribe(:events) { |on|
            on.message { |channel, message|
                puts message
            }
        }
    end
end

MyActor.new
sleep