Virtual Extension By Inversion of Responsibility (Second Draft)

[Neal Gafter]

Colin-

I like some aspects of this proposal.  Compared to defender methods,
there is no need for a special InterfaceName.super.method(...)
notation.  I like that it can be used to extend interfaces over which
the programmer does not have control: that enables pattern-based
frameworks and language extensions to be more generally useful (ala
LINQ).  An example of where that would be useful today is in the
specification of ARM blocks; if defined in terms of -> instead of .,
it can be retrofitted to many more types than would otherwise be
possible.  Defender methods don't allow that.

I don't like the use of annotations (@ExtensionSupport and
@ExtensionTarget) to change the meaning of declarations; this could be
done with context-sensitive keywords instead.  It is a little
unfortunate that the syntax is distractingly different from an
ordinary method invocation, even though the reader usually doesn't
care (now we'd have three different invocation syntax forms).

Cheers,
Neal

On Thu, Jun 17, 2010 at 8:09 PM, Collin Fagan <collin.fagan at gmail.com> wrote:
> Hi Everyone,
>
> I've put together a second draft of my proposal for virtual extension
> methods.
>
> http://www.box.net/shared/r24vvgma5p
>
> And yes *this* time they are really virtual. I welcome all comments.
>
> Thanks,
>
> Collin
>
>