用 rails 写了一个简单应用，使用 aliyun-oss-sdk-for-ruby 碰到如下错误，

/home/vagrant/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/aliyun-oss-0.7.0.1397365150/lib/aliyun/oss/extensions.rb:224: `@@{' is not allowed as a class variable name
/home/vagrant/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/aliyun-oss-0.7.0.1397365150/lib/aliyun/oss/extensions.rb:224: syntax error, unexpected end-of-input
        unless defined? @@{:instance_writer=>false}
                          ^ (SyntaxError)

源代码在此 (221 行起)

class Class # :nodoc:
  def cattr_reader(*syms)
    syms.flatten.each do |sym|
      class_eval(<<-EOS, __FILE__, __LINE__)
        unless defined? @@#{sym}
          @@#{sym} = nil
        end

        def self.#{sym}
          @@#{sym}
        end

        def #{sym}
          @@#{sym}
        end
      EOS
    end
  end

先把问题放到这里，看哪位大侠能解救我。明天继续搞，