Question

I accidentally noticed the following:

scala> class g[T](val x:T)   
defined class g

scala> val obj=new g[Int]('A')
obj: g[Int] = g@1082d45

scala> obj.x
res6: Int = 65

What is happening here? A typecast?

Answer 1

It’s upconversion of primitives. Primitive values will convert themselves to the next numerically-larger type if it seems like that is needed. So val s: Short = (0: Byte) works. Nothing converts to Char, but Char will become an Int, Long, Float, or Double if it needs to to be the right argument type.

The reason this is done is mostly because it’s how Java does it, but partly because getting an error off of val d: Double = 0 is really annoying since 0 of course fits into a Double with no problems whatsoever, and there’s no ambiguity about the type either.