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Fwd: C++ PATCH: PR 20599 (1/3)


I don't think this made it to the list...

---------- Forwarded message ----------
From: Doug Gregor <doug.gregor@gmail.com>
Date: Sep 19, 2006 10:34 AM
Subject: Re: C++ PATCH: PR 20599 (1/3)
To: Gennaro Prota <gennaro_prota@yahoo.com>
Cc: gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org


On 9/19/06, Gennaro Prota <gennaro_prota@yahoo.com> wrote:



On Mon, 18 Sep 2006 19:27:09 -0400, "Doug Gregor"
GCC could break this stale-mate by including experimental
implementations of these features. Then, the community at large can
experiment and better understand these features, finding (and fixing!)
problems before the ink dries on C++0x.

I mostly agree without your analysis. But I think it also matters having a relatively long period of experimentation.

I don't think it's the length of time for experimentation, but the
amount of time spent in aggregate. If 100 people play with the feature
for 2-3 hours, we'll get a much better sense of its capabilities and
limitations than if one person spends 300 hours using that feature.
It's extremely hard to get people to download and install a new
compiler to try out a language feature. I've found this with
ConceptGCC: each time I give a talk or a demonstration, people would
come up to me and say how much they want to have this feature in their
compiler. But few... very few... actually go download the compiler to
try it. The barrier of installing a new compiler is just to high. But
if they could just flip a switch in their current compiler, they will
try it.
Now you see why I am pushing for inclusion in a release, rather than
on a branch. A branch just doesn't give enough exposure for us to get
enough feedback.


This time it seems
to me that there's too much time pressure, both for the committee and
for vendors


By "this time" do you mean this committee meeting? This standard?
This feature?

If you mean this committee meeting, then I agree, somewhat. The issue
is that we keep counting backward from 2009 (the last year in which
we're supposed to ship C++0x), and realizing that there isn't much
time left. I don't know the complete details, but there's at least a
year's lag in approving the working draft, so we really need to have
the draft final by 2008. On the other side, once the Evolution Working
Group accepts a feature in principle, it takes at least a year before
we can get suitable "standardese" to put it in the working draft. So
if everything that will be C++0x gets accepted in Portland, we'd have
a year in the middle to make sure everything works together. Ask
someone who understands ISO rules better and you'll get a bleaker
picture :)


(speaking about the former I'm seriously worried for the
thread specification, for instance). Don't you think so?


It very much depends on the feature. I'm actually not that worried about threads, because there is a lot of interest in this do-or-die feature, and many smart people are working to make that happen.

Doug


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