Re: [boost] [phoenix] request for a mini-review. (Re: Phoenix as a Boost library)

Subject: Re: [boost] [phoenix] request for a mini-review. (Re: Phoenix as a Boost library)
From: Joel de Guzman (joel_at_[hidden])
Date: 2010-10-17 06:58:22

On 10/17/2010 6:38 PM, David Abrahams wrote:
> At Sun, 17 Oct 2010 13:01:08 +0800,
> Joel de Guzman wrote:
>>
>>> You could approximate it for up to 3-5 arguments. But you can't actually do it perfectly in C++03 even for 1 argument because you will erase rvalue-ness no matter what.
>>
>> Yeah, that's what we do for 03. Let's call it less-than-perfect forwarding.
>> It's the best we can do. Right now we have a PP constant for that. Mind you,
>> even 3 args is still quite expensive! Then we have 2 more PP constants
>> for all refs and another for all const refs.
>
> I think it's only useful to have one of those be higher than the first
> PP constant, because you'll just get ambiguities.

Yep. That's how it's done AFAIK.

Cheers,
-- 
Joel de Guzman
http://www.boostpro.com
http://spirit.sf.net