Re: [boost] [result_of] Allow result_of to work with C++11 lambdas

Subject: Re: [boost] [result_of] Allow result_of to work with C++11 lambdas
From: Nathan Crookston (nathan.crookston_at_[hidden])
Date: 2013-04-10 13:39:48

Hi Vicente,

Vicente J. Botet Escriba wrote:

> Le 10/04/13 19:12, Nathan Crookston a écrit :
>
> I think individual boost libraries shouldn't need to worry about the
>> macros.  Users may need to explicitly define one of the macros if they
>> develop on a compiler which supports decltype-based result_of, but wish to
>> support compilers without decltype.
>>
>> In short, I think that (with the decltype fallback) result_of *will*
>> choose
>> the best implementation, and (if the patch is applied) defining a macro to
>> explicitly select a back end should be done for cross-platform
>> compatibility reasons.
>>
>>  If you are right and after the patch result_of would provide the best we
> can do now, why the user would need to define any of these macros?
>

I think it would be uncommon for the user to define those macros.  Here's a
situation where it may be useful:

I have a library which I claim supports VC9 and Clang.  I do my development
with clang 3.2, and rely on some form of automated testing to verify it
works with MSVC.  I may commonly forget to add result_type or a nested
struct to my functors, since clang uses decltype.  After the Nth time, I
may, during my own development, #define BOOST_RESULT_OF_USE_TR1, just so
that I'm not continually breaking the VC9 build.

So again, I think it's uncommon.

Thanks,
Nate