module ThreadLocalExtension
  protected
  def self.included(base)
    base.extend ClassMethods
  end

  module ClassMethods
    def thread_local(name)
      klass, name = self.to_s, name.to_s

      (class << self; self end).send(:define_method, name, Proc.new do
        Thread.current["__#{klass}_#{name}__".intern]
      end)

      (class << self; self end).send(:define_method, name + "=", Proc.new do |value|
        Thread.current["__#{klass}_#{name}__".intern] = value
      end)
    end
  end
end