01-redis_hash_store.rb

module RedisHashStore
  module ClassMethods

  end

  module InstanceMethods
    def redis_hash_store_key
      @redis_hash_store_key ||= "#{self.class.redis_hash_store_key}:#{self.send(self.class.redis_hash_store_uid)}"
    end

    def hset key, val
      REDIS.hset(redis_hash_store_key, key, val)
    end

    def hincrby key, amt=1
      REDIS.hincrby(redis_hash_store_key,key,amt)
    end

    def hinc key
      REDIS.hincrby(redis_hash_store_key,key,1)
    end

    def hdec key
      REDIS.hincrby(redis_hash_store_key,key,-1)
    end

    def hget key
      REDIS.hget(redis_hash_store_key,key)
    end

    def hdel key
      REDIS.hdel(redis_hash_store_key,key)
    end

    def hgetall
      REDIS.hgetall(redis_hash_store_key)
    end
  end

  def self.included(receiver)
    receiver.extend         ClassMethods
    receiver.send :include, InstanceMethods

    receiver.instance_exec do
      def store_redis_hash_in key, args={}
        @@redis_hash_store_key = key
        @@redis_hash_store_uid = args[:uid] || :id
      end

      def redis_hash_store_key
        @@redis_hash_store_key
      end

      def redis_hash_store_uid
        @@redis_hash_store_uid
      end
    end
  end
end

03-foo.rb

class Foo
  include RedisHashStore
  store_redis_hash_in 'foo'
end

class FooFoo < Foo; end

04-bar.rb

class Bar
  include RedisHashStore
  store_redis_hash_in 'bar'
end

05-actual result

>> Foo.redis_hash_store_key
=> "bar"
>> FooFoo.redis_hash_store_key
=> "bar"
>> Bar.redis_hash_store_key
=> "bar"

06-intended result

>> Foo.redis_hash_store_key
=> "foo"
>> FooFoo.redis_hash_store_key
=> "foo"
>> Bar.redis_hash_store_key
=> "bar"