What's the Scala way to implement a retry-able call like this one?

Question

Still the newbie in Scala and I\'m now looking for a way to implement the following code on it:

@Override
public void store(InputStream source, String destin         


        

Answer 1

Here is one possible implementation:

def retry[T](times: Int)(fn: => T) = 
    (1 to times).view flatMap (n => try Some(fn) catch {case e: Exception => None}) headOption

You can use it like this:

retry(3) {
    getClient.putObject(request)
}

retry also returns Some[T] if body was processed successfully and None if body was only throwing exceptions.

---

Update

If you want to bobble up last exception, then you can take very similar approach but use Either instead of Option:

def retry[T](times: Int)(fn: => T) = {
    val tries = (1 to times).toStream map (n => try Left(fn) catch {case e: Exception => Right(e)}) 

    tries find (_ isLeft) match {
        case Some(Left(result)) => result
        case _ => throw tries.reverse.head.right.get
    }
}

Also, as you can see, at the end, instead of having only last exception, I have them all. So you can also wrap them in some AggregatingException if you want and then throw it. (for simplicity, I just throw last exception)