Re: [boost] forwarding-function macro library?

From: Isaac Dupree (isaacdupree_at_[hidden])
Date: 2008-08-12 08:06:16

Stjepan Rajko wrote:
> On Sat, Aug 9, 2008 at 6:57 AM, Isaac Dupree <isaacdupree_at_[hidden]> wrote:
>> Is there a macro library in Boost for making forwarding functions (the thing
>> that can only be done perfectly in C++0x, with decltype, rvalue references
>> and perhaps parameter packs)?
> 
> Perhaps the Boost.Functional/Forward library might be helpful to you
> (not a macro library for forwarding functions, but a more elegant
> solution for function objects).  It was accepted into boost but I'm
> not sure whether it has made it to trunk yet.  Here is the review
> announcement with links:

I see..
Only *declaring* the many-overloads once, might be helpful 
to the compiler (although there wasn't evidence presented 
either way -- just that the *preprocessing* wasn't the main 
overhead on most compilers).  For fixed-number-of-argument 
forwarding, it's rather less efficient.  I just wish one 
could do "using some_class::static_function" at namespace 
scope...

Another issue about I ran into perfect forwarding: about 
C++0x's "constexpr".  I was having trouble figuring out for 
sure... but it looked like it doesn't like const-reference 
or templated rvalue-reference arguments for constexpr 
function types.  Which would mean that there's no perfect 
forwarding in the presence of constexpr (a constexpr 
function with all non-reference arguments would be the only 
way).  (Did I miss something? Is it worth installing 
ConceptGCC to see if I can play around with it (on linux))?

-Isaac