Joel, maybe you can elaborate how the Concept/SFINAE approach manages with this problem.
Sure, in my head, we can define Concepts callee ThreadSafe, ExceptionSafe etc and just use BOOST_CONCEPT_REQUIRE on those (or the real C++0x concept maps) and have Concept Violation error when you try to call one function with improper settings. Then, IIRC there was planned to have SFINAE based on concept so we cna alos have function prunning (ie nice 'no such function f() defined' inthose case. Using BOOST.CC, I already do that for parallel computing enforcement: i have a type traits that I can specialize per obejct or function type basis and the concept class just check for this concept then I write: template<class F,class A> BOOST_CONCEPT_REQUIRE( (CalalbleObject<F>)(DataParallel<F>) , std::vector<boost::result_of<F(A)>::type> ) map( F f, std::vector<A>); if f is not a CallableObjec supporting data-parallelism (here I just check that is_dataparallel<F>::value is true) then the function is not permitted. Such a mechanism can be applied to what's describe in the article, or am I mistaken ?