From: Eric Niebler (eric_at_[hidden])
Date: 2008-04-13 15:42:38
Giovanni Piero Deretta wrote:
> On Sat, Apr 12, 2008 at 8:38 PM, Eric Niebler <eric_at_[hidden]> wrote:
> Giova*ll*i ?!?!?!
Whoops, sorry. :-P
>> conditional operator. Wish I thought of that. But it requires
>> types to be associated with integers via a global registry, so I can't
>> use it. Is there a way to avoid select() and result<>? It's easy with
>> typeof, but can you do it without?
> Here is a try. it probably will look more at home at an obfuscated C++ context.
> It works up to 5 types. Extending it beyond is a matter of a little of
> pp metaprogramming.
> The only O(N) template (that I can see) instantiation is
> template<class T> default_type::operator T();
Not a problem. It's a function template, so instantiating it would be
cheaper than instantiating a class template (I think), but you're not
even instantiating it. It doesn't even have a definition.
> And you do not pay for it if you do not use default_type (partially
> specializing common_type may work as an optimization).
> I'll try to get rid even of this.
> Even if there are very few template instantiations, compile time isn't
> that good. I thought that compile time integral expression
> computations were basically free. Maybe I'm missing something.
This solution is very clever! Why do you say that compile time is poor?
What are you benchmarking against?
-- Eric Niebler Boost Consulting www.boost-consulting.com
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