David Abrahams wrote:
on Tue Jun 02 2009, Eric Niebler <eric-AT-boostpro.com> wrote:
I read form the Wikipedia entry that Clang's C++ support is 2-3 years from being usable, though.
I wouldn't bet against Doug Gregor when he's firing on all cylinders :-)
I didn't know Doug was involved. That changes everything! :-)
From the user time, my recent changes make this test compile twice as fast for gcc-3.4 (cygwin). For MSVC, the wins are less dramatic.
Your point is taken, though ... instantiation count is merely a rule of thumb and the real measure is clock time. It is, in my experience and with compilers actually in use today, a very good rule of thumb, though.
Well, it's great to get the instantiation count down, but consider that what you're replacing it with may not be any faster :-)
See the comment above about a measured 2x speed-up.
If you *are* getting a win from PP metaprogramming, there's a good chance that you could improve the speed a lot more, e.g. by using the "z" parameter as described in http://www.boostpro.com/tmpbook/preprocessor.html#horizontal-repetition
Yep, I know about that, but generally avoid nested horizontal repetition. Nevertheless, I appreciate the suggestions. For anybody concerned about the nature of my changes, here is an example of the fat in Fusion I'm trimming: https://svn.boost.org/trac/boost/changeset/53566/trunk/boost/fusion/containe... -- Eric Niebler BoostPro Computing http://www.boostpro.com