Re: [Boost-users] boost::ptr_vector::sort with c++11 lambdas

Subject: Re: [Boost-users] boost::ptr_vector::sort with c++11 lambdas
From: Michel Morin (mimomorin_at_[hidden])
Date: 2011-11-12 12:00:38

Vicente J. Botet Escriba wrote:
>> We should proceed gradually even if N3276-decltype is available, because
>> * decltype-based result_of can break user codes with (unintended) use
>>   of result_of.
>> * Implementation of N3276-decltype might be buggy for some time.
>>
> Thanks for the clarification. So if IUC, the use of
> BOOST_RESULT_OF_USE_DECLTYPE in the user code could break other parts of her
> application, isn't it?

Right. There are two types of breakage.
(But note that the correct support of the traditional result_of protocol
and the correct usage of result_of should not make any breakage with
BOOST_RESULT_OF_USE_DECLTYPE + N3276-decltype. So, I think,
you don't have to worry about the breakage too much.)

1) Breakage caused by type-completeness requirement of non-N3276-decltype
Boost.Proto uses boost::tr1_result_of to avoid this problem.
boost::tr1_result_of uses the traditional implementation of result_of
even if BOOST_RESULT_OF_USE_DECLTYPE is defined.

2) Breakage caused by incorrect support or incorrect usage of result_of
Some codes using Boost.Fusion or Boost.Phoenix fail to compile
if BOOST_RESULT_OF_USE_DECLTYPE is defined.
    http://thread.gmane.org/gmane.comp.parsers.spirit.general/24027
    https://svn.boost.org/trac/boost/ticket/5687

Regards,
Michel