Virtual extension methods -- a strawman design

[Brian Goetz]

> Could you not add closures first and save the library changes for a
> future update? The problem of retro-fitting the core API's does make
> sense in terms of time frame but it's kind of now or never (or a few
> years from now) in terms of having another opportunity to add them
> without another new major version number isn't it?

Yes, and it is quite possible we may end up doing just that.

To address the "another opportunity" point, note that the mechanism does (or 
should) allow for gradual evolution of interfaces (by dividing methods into 
"original" and "added later", but you get more than one chance to add later.)

 > It would be more ideal to have the libs retro-fitted but having the
 > language feature would be even more important in my opinion..Users can
 > find "satisifcation" in a future release while library designers /
 > toolers / etc can quietly add support for it in anticipation of a
 > future release update that expands and does the retro-fitting work..
 > maybe.

Quite so.  But of course that depends on many things -- including the time lag 
between now and 7, and the time lag between 7 and 8.