"Arkadiy Vertleyb" <vertleyb@hotmail.com> writes:
"David Abrahams" <dave@boost-consulting.com> wrote
Okay, how about the one enclosed here, then?
Now you have both size() and size_<> instantiated LIMIT_SIZE times ;-)
According to Eric, you need something like size_<> to workaround vc++ bugs, though.
Not if the expression is simplified. It's really multiple calls to sizeof what drives the compiler crazy.
Okay, let me try one more. I think this one gets close to the minimal number of instantiations required to work around VC++ bugs.
Still, select<> is instantiated LIMIT_SIZE times...
Yes, but not LIMIT_SIZE * N, where N is the number of different types passed to BOOST_TYPEOF. So it's a one-time cost, which is better than what I posted earlier.
The beauty of the ugly solution with the conditional operator is that it brings the algorithm complexity, in terms of template instantiations, to O(m), where m is the real size of the vector. True, we pay by doubling the amount of template lookups, and expression evaluations, but it looks like it pays.
OK.
It's a pity that VC8 chokes on this in some contexts -- maybe we'll be able to get MS to fix it before the real thing comes out.
Yes, I have got one of their engineers working on it :)
Until then, I believe we should specialcase the VC8, and I think your first suggestion, with no separate size function will do the job fine.
I think my latest is better.
We could even limit this to dependent contexts, since I don't think this problem exists outside templates. However your other suggestion, that allows to remove _TPL, makes this impossible. Still, I love the idea of removing _TPL so much that I am willing to pay this price...
Agreed. -- Dave Abrahams Boost Consulting www.boost-consulting.com