Re: [boost] Active objects?

From: Cory Nelson (phrosty_at_[hidden])
Date: 2005-11-02 01:02:59

On 11/1/05, Scott Woods <scottw_at_[hidden]> wrote:
>
> ----- Original Message -----
> From: "David Abrahams" <dave_at_[hidden]>
> To: <boost_at_[hidden]>
> Sent: Wednesday, November 02, 2005 10:05 AM
> Subject: Re: [boost] Active objects?
>
>
> > "Reece Dunn" <msclrhd_at_[hidden]> writes:
> >
> > > Cory Nelson wrote:
> > >>I saw that presentation too, it is very impressive and I can't wait to
> > >>see what comes of it.
> > >
> > > Yeah, having active and futures support would make writing multithreaded
> > > apps a dream.
> > >
> > >>I would love to see something like this go into boost but somehow I
> > >>don't think it could be done elegantly without language and compiler
> > >>support.  Definitely wouldn't complain if someone proved me wrong :)
> > >
> > > Active objects would be very hard to do *automatically* since the object
> is
> > > a thread (very neat concept)
> >
> > Also a very old concept.  See Simula.  Kristen Nygaard would be
> > pleased.
> >
> > However, it sounds a lot like the COM "apartment model," which I've
> > never had the pleasure to use, but whose usability I recall my
> > colleagues complaining bitterly about.
> >
>
> Huh. Had thought the "active object" term had originated from work by D.
> Schmidt.
> Not too many complaints about his version of things, even if working with
> some
> implementations (CORBA) can be unwieldy.
>
> H. Sutter's version looks nice. The idea that calls on an object can be
> queued for
> execution at some later time is useful. Successfully hiding the details
> would be cute.
>
> I hope it's fair to also say that it's not a solution to the nasty async
> problem that I
> typically run into.
>
> Active objects (a la Sutter) appear to be reinforcing the standard "call"
> model
> over async activity. This is good because it is familiar to us. Symmetric
> interaction
> between groups of peer objects is a different model of operation. Any object
> can "call" any other object and there is no "return" (i.e. future). Most of
> my
> async-programming problems seem to fall into the latter category.
>
> In summary, Mr Sutters AOs would deliver a slick solution to a certain class
> of application. I'm guessing it's not intended as the "final" solution to
> all
> async development?

In the presentation he gave reasons for needing to have the future<>
and call wait() etc.  In the end it seems to boil down to having a
point to reliably catch exceptions and other errors.

But he also mentioned clearly that it's just a concept they've been
toying with and that they have no strong commitment to it.

> Cheers.
>
>
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--
Cory Nelson
http://www.int64.org