CODEWITHSUNDEEP
scalascala-macrosscala-macro-paradise
tkroman
tkroman

Reputation: 4798

Is it possible to have macro annotation parameters (and how to get them)?

I have some data source that requires wrapping operations in transactions, which have 2 possible outcomes: success and failure. This approach introduces quite a lot of boilerplate code. What I'd like to do is something like this (the same remains true for failures (something like @txFailure maybe)):

@txSuccess(dataSource)
def writeData(data: Data*) {
  dataSource.write(data)
}

Where @txSuccess is a macro annotation that, after processing will result in this:

def writeData(data: Data*) {
  val tx = dataSource.openTransaction()

  dataSource.write(data)

  tx.success()
  tx.close()
}

As you can see, this approach can prove quite useful, since in this example 75% of code can be eliminated due to it being boilerplate.

Is that possible? If yes, can you give me a nudge in the right direction? If no, what can you recommend in order to achieve something like that?

Upvotes: 2

Views: 67

Answers (1)

Gabriele Petronella
Gabriele Petronella

Reputation: 108101

It's definitely possible, but you don't necessarily need macros for the task.

Here's a simple solution, which doesn't use macros

object DataOperation {
  def withTransation[T](dataSource: DataSource)(f: () => T): T = {
    val tx = dataSource.openTransation()
    f()
    tx.success()
    tx.close()
  }
}

And use it like

DataOperation.withTransation(dataSource) {
  dataSource.write(data)
}

Upvotes: 0

Related Questions