Suggestions for Java Generics Semantics in Java Version 7.0 _ Resurrected

[David Herron]

Hey Alex,

This is a very well put argument about the situation.  I certainly don't
have the basis for commenting on the technological underpinnings of anything
you have said.

The thing I want to point to is that item #3 follows a "Sun provides the
technology, you guys consume the technology" attitude.  In the spirit of an
open source community process perhaps #3 could be reworded to say that Sun's
priorities are clear from where Sun is placing it's R&D dollars, and if a
group were to form in the community to implement reification ...etc...

In other words, notwithstanding the prestige of the names you listed in
point #2, it may be possible with enough work for some set of people to
implement reification.  I would hope that if the community were to do it,
that it could be accepted into the OpenJDK.  Maybe some people in the
community have a different prioritization of needs than Sun has?

- David Herron


On Wed, Jun 17, 2009 at 12:21 PM, Alex Buckley <Alex.Buckley at sun.com> wrote:

> 1) Sun's bug database categorizes an entry as either a defect or a request
> for enhancement. Bug 5098163 is, rightly, a request for enhancement. It is
> not a defect that type erasure exists. I will say that again. Type erasure
> is not a bug. It is a feature.
>
> 2) The reason it is a feature is that many experts - including but not
> limited to Philip Wadler, Martin Odersky, Gilad Bracha, Joshua Bloch, and
> Neal Gafter - worked for many years on crafting a generic type system that
> allowed people to migrate their non-generic clients and libraries smoothly.
> Reified generics would have made that migration more complex. If you don't
> know why, find out.
>
> 3) While there were good reasons for avoiding it, there is no doubt that
> reified generics make the Java language itself more regular. No doubt at
> all. The question we face TODAY is, are reified generics MORE valuable than
> other features that Sun can add to the Java platform. Evidently not, since
> Sun is working on other features.
>
> Again, I don't want to prolong this conversation, but perhaps you could say
> which JDK7 feature(s) you would drop to make room for reified generics? You
> can choose from the list at
> http://openjdk.java.net/projects/jdk7/features/
>
> Alex
>