Packages

class Defers[T] extends AnyRef

Construction Defers: defer/recover is alternative mechanism to exception handling, simular to one in Go language.

We use one hidden in go and goScope construct are transformed to withDefers usage with help of macroses.

It is also possible to use one unsugared (as in next example), but this is a bit verbose.

def parseCsv(fname: String): Either[String, Seq[Seq[Double]]] =
 withDefer[Either[String,Seq[Seq[Double]]]]{ d =>
   val in = Source.fromFile(fname)
   d.defer{
      var r = d.recover{
                case FileNotFoundException => Left("fileNotFound")
              }
      if (!r) in.close()
      d.recover {
        case ex: Throwable => Left(ex.getMessage)
      }
   }
   val retval:Either[String,Seq[Seq[Double]]] = Right{
       for( (line, nLine) <- in.getLines.toSeq zip Stream.from(1) ) yield withDefer[Seq[Double]] { d =>
          line.split(",") map { s=>
                                d.defer{
                                 d.recover{
                                    case ex: NumberFormatException =>
                                      throw new RuntimeException(s"parse error in line ${nLine} file ${fname} ")
                                 }
                                }
                                s.toDouble
                              }
       }.toSeq
     }
   retval
}

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Instance Constructors

  1. new Defers()

Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
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  2. final def ##(): Int
    Definition Classes
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  3. final def ==(arg0: Any): Boolean
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  4. final def asInstanceOf[T0]: T0
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  5. def clone(): AnyRef
    Attributes
    protected[java.lang]
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    Annotations
    @throws( ... )
  6. def defer(body: ⇒ Unit): Unit

    can be used in main block (which can be plain or async) and store body for defered execution after evaluation of main block

  7. final def eq(arg0: AnyRef): Boolean
    Definition Classes
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  8. def equals(arg0: Any): Boolean
    Definition Classes
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  9. def finalize(): Unit
    Attributes
    protected[java.lang]
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    @throws( classOf[java.lang.Throwable] )
  10. final def getClass(): Class[_]
    Definition Classes
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  11. def hashCode(): Int
    Definition Classes
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  12. final def isInstanceOf[T0]: Boolean
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  13. final def ne(arg0: AnyRef): Boolean
    Definition Classes
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  14. final def notify(): Unit
    Definition Classes
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  15. final def notifyAll(): Unit
    Definition Classes
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  16. def processResult(x: Try[T]): T

    called after execution of main block, where all 'defered' blocks will be executed in one thread in LIFO order.

  17. def recover(f: PartialFunction[Throwable, T]): Boolean

    called inside defer blocks, where argument(t)

  18. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
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  19. def toString(): String
    Definition Classes
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  20. def tryProcess(x: Try[T]): Try[T]
  21. final def wait(): Unit
    Definition Classes
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    Annotations
    @throws( ... )
  22. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
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    @throws( ... )
  23. final def wait(arg0: Long): Unit
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