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

Chris Jefferson chris@bubblescope.net
Tue Sep 19 15:22:00 GMT 2006

On 19/09/06, Doug Gregor <doug.gregor@gmail.com> wrote:
> 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.

Connected to this, being on a branch means very little exposure (I
have contributed to libstdc++, yet managed to miss for a long time
that I ConceptGCC was available).

Perhaps the flag to enable the features should be something like
-UNSTABLE_c++0x? That is very ugly looking, but surely that is partly
the point, and it should be clear it will be removed later.

What I would personally like to see would be the ability to enable
these flags for certain headers. I'm not sure if this is feasable, but
I imagine it would be of benefit both to g++ and to the features
themselves if libstdc++ can start using them as soon as possible.


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