Ensuring template argument is descendant of class

[Brian Rogoff]

On Friday, 13 December 2013 at 05:55:09 UTC, H. S. Teoh wrote:
> On Fri, Dec 13, 2013 at 06:42:26AM +0100, Brian Rogoff wrote:
>> I'm sympathetic to this POV, or something similar. For 
>> example, a
>> multiyear plan to deprecate the 'is' syntax and replace it with
>> something better, in the current D. I'm not a fan of gratuitous
>> changes which make the language unstable, but if there were a
>> pleasing design to replace 'is' I'd like to think that D users 
>> could
>> change the relevant sources given a long enough deprecation 
>> window.
>
> I vote for this. Good luck convincing Walter, though.

Step 1 is to come up with a set of better design alternatives,
and a transition plan, etc. I'm pretty sure I've read posts from
Walter on this forum that agree with the current 'is' is far from
ideal, so maybe convincing him is not as hard as you think,
though I imagine he has bigger fish to fry these days. Still, it
would be encouraging if the D community could address the general
issue of *not* being forced to keep bad designs forever.

-- Brian