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

I'd suggest this -

def retry[T](n: Int)(code: => T) : T = { 
  var res : Option[T] = None
  var left = n 
  while(!res.isDefined) {
    left = left - 1 
    try { 
      res = Some(code) 
    } catch { 
      case t: Throwable if left > 0 => 
    }
  } 
  res.get
} 

It does:

scala> retry(3) { println("foo"); }
foo

scala> retry(4) { throw new RuntimeException("nope"); }
java.lang.RuntimeException: nope
        at $anonfun$1.apply(:7)
        at $anonfun$1.apply(:7)
        at .retry(:11)
        at .(:7)
        at .()
        at RequestResult$.(:9)
        at RequestResult$.()
        at RequestResult$scala_repl_result()
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at scala.tools.nsc.Interpreter$Request$$anonfun$loadAndRun$1$$anonfun$apply$17.apply(Interpreter.scala:988)
        at scala.tools.nsc.Interpreter$Request$$anonfun$loadAndRun$1$$anonfun$apply$17.apply(Interpreter....
scala> var i = 0 ;
i: Int = 0

scala> retry(3) { i = i + 1; if(i < 3) throw new RuntimeException("meh");}

scala> i
res3: Int = 3

It can probably be improved to be more idiomatic Scala, but I am not a big fan of one-liners that require the reader to know the entire standard library by heart anyways.