Ruby 如何在rails 3.2模型中包含动态代码？

在rails 3.2应用程序中，我们希望在模型中保持工作流定义代码的动态性。以下是工作流定义代码：

include Workflow
workflow do     
  state :new do
    event :submit, :transitions_to => :being_reviewed
  end
  state :being_reviewed do
    event :approve, :transitions_to => :approved
    event :reject, :transitions_to => :rejected
  end
  state :approved
  state :rejected
end

上面的代码作为存储在变量

工作流\u pdef

中的

字符串返回。我们的问题是如何使用
eval（workflow\u pdef）
动态地
在模型中包含上述代码
 
workflow\u pdef=：已批准
事件：拒绝，：转换到=>：拒绝
结束
国家：批准
国家：拒绝
结束
代码
#包含在每个实例中
甲级；结束
A.class\u评估工作流程\u pdef
#仅包含在实例“b”中
乙级;；结束
b=b.新的
b、 实例\u评估工作流\u pdef
以下是我们所做的：

include Workflow
Worflow do
  eval(workflow_pdef)
end

那么工作流_pdef的字符串是：

workflow_pdef = "     
    state :new do
      event :submit, :transitions_to => :being_reviewed
    end
    state :being_reviewed do
      event :approve, :transitions_to => :approved
      event :reject, :transitions_to => :rejected
    end
    state :approved
    state :rejected
  "

工作流定义的功能部分可能会变得动态。
必须在模型中执行pdef字符串。您可以使用
self.class
或
self
替换类“a”或实例“b”，以便在当前模型上运行
workflow_pdef = "     
    state :new do
      event :submit, :transitions_to => :being_reviewed
    end
    state :being_reviewed do
      event :approve, :transitions_to => :approved
      event :reject, :transitions_to => :rejected
    end
    state :approved
    state :rejected
  "