---- Message d'origine ----
De : "Robert Ramey" <ramey@rrsd.com> À : boost@lists.boost.org Objet : Re: [boost] question about C++11 guidelines Date : 03/05/2012 08:30:06 CEST
Eric Niebler wrote:
Say I'm rewriting an existing Boost library and targeting C++11 users. I plan to ship C++03 and C++11 versions of my library side-by-side, so back-compat isn't an issue for the new code. Is there a reason to prefer using Boost's versions of utilities like enable_if, type traits, integral constant wrappers (e.g. mpl::int_), tuples, etc., over the now-standard ones?
I'm leaning toward using std:: where I can, and falling back on Boost's versions only when there is a compelling reason.
Isn't easier to just use the boost versions knowing that they will be implemented in the most efficient/appropriate way for the compiler in question?
From what I understood, std::make_shared is more efficiently implemented on some platforms that boost::make_shared, so I would not assume that boost version is better than the version provided by the compiler. From a boost user point of view, I have another issue with boost compatibility with C++11, that is not used by either proposal: - If types such as boost::shared_ptr and boost::tuple are used in the library boost.sampleLib, whenever I want to interface boost.sampleLib with other code that was written without boost, and makes use of std::shared_ptr or std::tuple, I have troubles, and need to convert/copy objects - If types such as std::shared_ptr and std::tuple are used in the library boost.sampleLib, whenever I want to interface boost.sampleLib with other code that was written with boost, and makes use of boost::shared_ptr or boost::tuple, I have troubles, and need to convert/copy objects The more I think of it, the more I believe the right solution is not to have two different types, but making sure that on a platform where std::shared_ptr exists, boost::shared_ptr is defined as an alias to std::shared_ptr, and just the same for all C++11 types that were first developped with boost. Frankly, I have been using boost on VC10 that contains std::shared_ptr for quite some time now, and I can say it is quite a pain, there are many subtle compilation problems that all come down to the fact that there are duplicated types with the same name in the same program. For instance: struct A { A(int i); A(std::vector<int> const &v); }; using boost::make_shared; std::vector<int> v; boost::shared_ptr<A> p1 = make_shared<A> (3); // Works boost::shared_ptr<A> p1 = make_shared<A> (v); // Does not work, there is no conversion from std::shared_ptr to boost::shared_ptr -- Loïc