From 6b3ef4f1676adcbe6dbdbf59a3bd359f339b0626 Mon Sep 17 00:00:00 2001 From: Adriaan Moors Date: Mon, 4 Jun 2012 15:35:35 +0200 Subject: turn unchecked type patterns into checked ones the pattern `(_: T)` is made checkable using (ct: ClassTag[T]).unapply by rewriting it to `ct(_: T)` (if there's a ClassTag[T] available) similarly for extractors: if the formal type of the unapply method is an uncheckable type, wrap in the corresponding classtag extractor (if available) don't trigger rewrite on non-toplevel unchecked types (i.e., only look at type constructor part of T when looking for unchecked types) TODO: find outer match to figure out if we're supposed to be unchecked would like to give users a chance to opt-out from the wrapping, but finding the match to which this pattern belongs turned out to be tricky... --- test/files/run/virtpatmat_typetag.scala | 36 +++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) create mode 100644 test/files/run/virtpatmat_typetag.scala (limited to 'test/files/run/virtpatmat_typetag.scala') diff --git a/test/files/run/virtpatmat_typetag.scala b/test/files/run/virtpatmat_typetag.scala new file mode 100644 index 0000000000..c1b1fd813a --- /dev/null +++ b/test/files/run/virtpatmat_typetag.scala @@ -0,0 +1,36 @@ +import reflect.{ClassTag, classTag} + +trait Extractors { + type T + implicit val tTag: ClassTag[T] + object ExtractT { + def unapply(x: T) = Some(x) + } + def apply(a: Any) = a match { + case ExtractT(x) => println(x +" is a "+ implicitly[ClassTag[T]]) + case _ => println(a+ " is not a "+ implicitly[ClassTag[T]] +"; it's a "+ a.getClass) + } +} + +object Test extends App { + def typeMatch[T: ClassTag](a: Any) = a match { + case x : T => println(x +" is a "+ implicitly[ClassTag[T]]) + case _ => println(a+ " is not a "+ implicitly[ClassTag[T]] +"; it's a "+ a.getClass) + } + + // the same match as typeMatch, but using an extractor + def extractorMatch[S: ClassTag](a: Any) = + (new Extractors { type T = S; val tTag = classTag[T] })(a) + + typeMatch[Int](1) + typeMatch[Integer](1) + typeMatch[String](1) + typeMatch[Any](true) + typeMatch[String]("woele") + + extractorMatch[Int](1) + extractorMatch[Integer](1) + extractorMatch[String](1) + extractorMatch[Any](true) + extractorMatch[String]("woele") +} \ No newline at end of file -- cgit v1.2.3