storage.rb

require 'redis'

class Storage

  def initialize(name:)
    @name = name
    @storage = Redis.new
  end

  def add(value)
    storage.sadd(name, value)
  end

  def all
    storage.smembers(name)
  end

  def size
    storage.scard(name)
  end

  def clear
    storage.del(name)
  end

  private
    attr_reader :name, :storage
end