Idea how to implement VT/VO compatibility in JVM

Maurizio Cimadamore maurizio.cimadamore at oracle.com
Thu Jan 22 13:21:19 UTC 2015


On 22/01/15 13:11, Stéphane Épardaud wrote:
> `ArrayList<int>` is special, mostly due to the fact that I'm not sure 
> we can retrofit `Integer` to be a value type, so existing primitives 
> may not get the `List<int> === List<Integer>` that I suggest for value 
> types (though I'd be very interested in making this work). 
Sorry - didn't want fold two problems into one - let's keep things 
simple and think about:

Object o = new ArrayList<Point>();

where Point is a value class.

Now,

o instanceof ArrayList<Point> //?

Or, as translated by our current prototype:

o instanceof ArrayList${0=QPoint;} //yes!

But how about:

o instanceof ArrayList<?> //?

Maurizio





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