I've got a List[Any]
of values and a list of corresponding ClassManifest[_]
s, storing values' original types. 开发者_运维百科How do i cast some value from list back to it's original type?
def cast[T](x: Any, mf: ClassManifest[T]): T = x.asInstanceOf[T]
doesn't work.
Thank You for your answers.
That can't ever possibly work, as the return type of cast
will always be taken as the highest common supertype of whatever T
is restricted to. There's no way it can be made any more specific at compile time.
If you're trying to build a strongly-typed collection of disparate types, then what you really want is an HList:
http://jnordenberg.blogspot.com/2008/09/hlist-in-scala-revisited-or-scala.html
The way to use a Class
instance in Java/Scala to cast an object is to use the Class.cast
method. So you may think that you could do:
mf.erasure.cast(x) //T
But this will not work, because mf.erasure
is a Class[_]
(or a Class<?>
in Java), so the cast is meaningless (i.e. offers no extra information). This is (of course) one of the drawbacks in using non-reified generics.
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