Re: Imitation is the sincerest form of flattery

[amir@iae.nsk.su (Amir Yantimirov)]

Robert A Duff <bobduff@shell01.TheWorld.com> wrote in message news:<wccn0jjv1jo.fsf@shell01.TheWorld.com>...
> "Frank J. Lhota" <NOSPAM.lhota.adarose@verizon.net> writes:
> 
> > If there is a way to get the effect of tagged scalar types without a big hit
> > on efficiency, however, it would certainly be helpful.

<snip>

> So the question is whether a language can provide extensible scalars
> with dispatching calls without slowing code that doesn't need that
> power.  I think the answer is yes: don't store the tag with every
> object.  Instead, gin it up when calling a class-wide operation.
> So "+" on normal (non-class-wide) integers can be a single machine
> instruction, and integers can be stored as a single word.  The compiler
> can determine when to gin up a tag -- no need for explicit boxing
> operations.
> 
> - Bob

Exactly. Only in my C++ head it is sounds as "address of particular
interface dispatch routine" instead of "tag". :)

http://www174.pair.com/yamir/programming/interfaces.htm

Amir Yantimirov