CODEWITHSUNDEEP
scalaenumeration
WestCoastProjects
WestCoastProjects

Reputation: 63022

Accessing (/importing) Scala Enumerations

For the following HwLogger.PersisterType enumeration:

object HwLogger extends Serializable {

  object PersisterType extends Enumeration {
    type Persisters = Value
    val FilePersister, HdfsPersister, SocketPersister = Value
  }

}

In the companion class - how do we access it? Notice the slew of imports below .. 

class HwLogger extends Serializable {
  import collection.mutable.ArrayBuffer
  import HwLogger.PersisterType._
  import HwLogger.PersisterType
  var persisterTypes = ArrayBuffer[PersisterType]()   // Compiler says " error: not found: type PersisterType"
  def setDefaults : Unit = {
    import PersisterType._
    persisterTypes ++ FilePersister ++ HdfsPersister 
  }

}

UPDATE After the accepted answer (and syntax correction on the arraybuffer append operators) here is the corrected code:

object HwLogger extends Serializable {

  object PersisterType extends Enumeration {
    type Persisters = Value
    val FilePersister, HdfsPersister, SocketPersister = Value
  }

}

class HwLogger extends Serializable {
  import collection.mutable.ArrayBuffer
  import HwLogger.PersisterType._
  import HwLogger.PersisterType
  var persisterTypes = ArrayBuffer[Persisters]()    // This is the fix (Persisters instead of PersisterType)
  def setDefaults : Unit = {
    import PersisterType._
    persisterTypes :+ FilePersister :+ HdfsPersister
  }

}

** Another update **

Changing the enumeration object will avoid the hassles:

object HwLogger extends Serializable {

  object PersisterType extends Enumeration {
    type PersisterType = Value    // Changed the "type" to be same as object name
    val FilePersister, HdfsPersister, SocketPersister = Value
  }

}

class HwLogger extends Serializable {
  import collection.mutable.ArrayBuffer
  import HwLogger.PersisterType._
  import HwLogger.PersisterType
  var persisterTypes = ArrayBuffer[PersisterType]()    // Revert back to PersisterType
  def setDefaults : Unit = {
    import PersisterType._
    persisterTypes :+ FilePersister :+ HdfsPersister
  }

}

Upvotes: 2

Views: 36

Answers (1)

wingedsubmariner
wingedsubmariner

Reputation: 13667

The type of elements in the Enumeration is Persisters, not PersisterType. PersisterType is only a value. You do need to import the types and values inside of PersisterType to use the Enumeration.

class HwLogger extends Serializable {
  import collection.mutable.ArrayBuffer
  import HwLogger.PersisterType._
  val persisterTypes = ArrayBuffer[Persisters]()
  def setDefaults: Unit = {
    persisterTypes += FilePersister += HdfsPersister 
  }
}

Upvotes: 3

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