Scala 对象反射

发布于 2024-12-11 02:28:06 字数 365 浏览 0 评论 0原文

如果我有以下 scala 对象：

object CustomerState {
   val PENDING = "pending"
   val TRIAL = "trial"
   val PAYING = "paying"
   val DEACTIVATED_TRIAL = "deactivated_trial"
   val DEACTIVATED_PAYING = "deactivated_paying"
}

如何获取所有 val 值的列表？在这种情况下，我希望获得一个列表（“待处理”、“试用”、“正在支付”、“deactivated_trial”、“deactivated_paying”）

提前致谢，托德

原文

If I have the following scala object:

object CustomerState {
   val PENDING = "pending"
   val TRIAL = "trial"
   val PAYING = "paying"
   val DEACTIVATED_TRIAL = "deactivated_trial"
   val DEACTIVATED_PAYING = "deactivated_paying"
}

How can I obtain a list of all the val values? In this case, I'm looking to get a List of ("pending", "trial", "paying", "deactivated_trial", "deactivated_paying")

Thanks in advance,
Todd

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余罪 2024-12-18 02:28:06

目前我认为你能做的最好的事情就是获取所有零参数方法的列表（因为这就是 val 被编译成的）并调用它们：

CustomerState.getClass.getMethods.toList.filter(_.getParameterTypes.isEmpty).map(_.invoke(CustomerState))

将会有一个 Scala- 2.10 中特定的反射库，这将使事情变得更好。

At the moment I think the best you can do is to get a list of all zero-argument methods (since that's what vals are compiled to) and call them:

CustomerState.getClass.getMethods.toList.filter(_.getParameterTypes.isEmpty).map(_.invoke(CustomerState))

There is going to be a Scala-specific reflection library in 2.10, which will make things better.

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吻安 2024-12-18 02:28:06

您不应该使用 Enumeration?

例子：

object Main extends Application {

   object CustomerState extends Enumeration {
     type CustomerState = Value
     val Pending, Trial, Paying, Deactivated = Value
   }

   import CustomerState._

   CustomerState.values foreach println // Will print each value
 }

Shouldn't you be using an Enumeration?

Example:

object Main extends Application {

   object CustomerState extends Enumeration {
     type CustomerState = Value
     val Pending, Trial, Paying, Deactivated = Value
   }

   import CustomerState._

   CustomerState.values foreach println // Will print each value
 }

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