Idea how to implement VT/VO compatibility in JVM

Maurizio Cimadamore maurizio.cimadamore at
Thu Jan 22 14:09:25 UTC 2015

On 22/01/15 13:58, Stéphane Épardaud wrote:
> On 01/22/2015 02:56 PM, Maurizio Cimadamore wrote:
>> You asked for 'holes' - I gave you some :-)
> And I'm glad you did, this is constructive! But these aren't holes 
> yet, they're things to implement ;) I was genuinely asking for more of 
> such information: that's useful.
Well, to some extent, everything falls in the category of 'things to 
implement'. To be honest, it's not very clear from your emails how you 
plan to tackle those issues, and I don't mean in terms of C++ Hotspot 
code, but merely in terms of how things should be wired up. Saying there 
should be _some kind_ of instanceof support sounds a bit vague-ish?

Backing up a bit, there are two dimensions to the problem you are trying 
to solve; one is to have specialized(A) and erased(A) to respond to the 
same sets of messages; I think your strategy there ticks the boxes; yes, 
it leaves field access a bit behind, but let's say that's collateral 
damage (although you need to prove that this won't come up so frequently 
that it would represent a real source compatibility threat).

The second dimension is to have specialized(A) 'is-a' erased(A) - and 
this is the part of the story that looks less clear.


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