scala good code

1akka actor  case class

Messages and immutability

IMPORTANT: Messages can be any kind of object but have to be immutable. Scala can’t enforce immutability (yet) so this has to be by convention. Primitives like String, Int, Boolean are always immutable. Apart from these the recommended approach is to use Scala case classes which are immutable (if you don’t explicitly expose the state) and works great with pattern matching at the receiver side.

Here is an example:

// define the case class
case class Register(user: User)
 
// create a new case class message
val message = Register(user)

2

Array.tabulate[BlockObjectWriter](numBuckets) { bucketId =>
          val blockId = ShuffleBlockId(shuffleId, mapId, bucketId)
          val blockFile = blockManager.diskBlockManager.getFile(blockId)
          // Because of previous failures, the shuffle file may already exist on this machine.
          // If so, remove it.
          if (blockFile.exists) {
            if (blockFile.delete()) {
              logInfo(s"Removed existing shuffle file $blockFile")
            } else {
              logWarning(s"Failed to remove existing shuffle file $blockFile")
            }
          }
          blockManager.getDiskWriter(blockId, blockFile, serializer, bufferSize)
        }

3    a with b  (b是个trait动态混入)

4 for yield

5  getorelse