Re: [boost] boost::result_of and C++03

From: Eric Niebler (eric_at_[hidden])
Date: 2008-04-10 12:00:23

shunsuke wrote:
> Eric Niebler wrote:
>>> As shown above, lvalue/rvalue-ness doesn't guarantee the complete safety.
>> I think your argument is specious.
> 
> I just show a counter-example.
> It might not be a real use case, though.
> I think
> 
>      int i;
>      /* perform elaborate calculations for i. */
>      return make_tuple(rvalue(i));
> 
> seems odd.

I actually agree. I've looked again at fusion::make_tuple and I see I 
misremembered its behavior. It always stores arguments by value unless 
the argument is a reference_wrapper. That seems reasonable, even in C++0x.

So maybe I'm coming around to thinking that function objects that do 
something different with lvalues and rvalues are always a bad idea, even 
in C++0x. Not sure yet what the implications are for proto transforms.

-- 
Eric Niebler
Boost Consulting
www.boost-consulting.com