Hi, I made notes in the Modern C++ session. You can also find them on the Wiki here: https://wiki.qt.io/QtCS2015_ModernCpp but I was requested to also post them here on the ML. If you were there and remember things differently, please edit and post a reply with corrections.
====== Sunday June 7, 10:00 AM Impact on supported compilers: VS2012 from 5.6. onwards and LTS release Discussed more in depth with the deprecation session What kind of features do we want, and what version of C++? 11? 14? What are the minimum requirements, even if we don’t rely on the existance of the feature? Qt is 5-8 years behind on C++, due to its nature. Auto, constexpr, lambda’s, r-value ref, decltype, nullptr, … (missed the rest). From compiler detection Variadic templates? We don’t use too many templates at all… QNX is not a problem in terms of compatibility. Gcc needs 4.7 for decent support of modern cpp. OS/X on gcc is dead, use clang instead. For windows embedded (EC) rely on MSVC 2012. Available for use then: * Auto * decltype * nullptr * r-value ref * lambda * class enum * explicit overrides Not available for use are: * uniform initialization and constexpr (is broken in VS2013.) * Explicit conversions, * = default, * = deleted, * inheriting constructors, * noexcept C++/11 needed for user applications as well then. It also lightens the maintenance burden. When to use? ============ Don’t go overboard. We need some guidelines. QtCreator team has experience. r-value, deltype are no-brainers. Class enums are a bit more of a discussion. It needs testing, and do we want that in the API? There is an inconsistency with existing API. The Qt:: scope is a big collection that would have been clearer. Auto is for use in code, not in API. Use auto where the type is (implicity) also on the right side. Iterators is a prime example. Creator may be used as a rule of thumb: if creator can’t follow them, don’t use them. Nullptr should be used in the headers, they need to be cleaner than the implementation. In source pointers: where it increases readability. Where it is not unclear, feel free to use 0 instead. It may cause some minor source incompatibilities. Don’t change existing code for the sake of this. Library use ========= We can’t detect the version, but we might require a minimum? Wishlist : * std::initialize lists * std::move * std::function * type traits (including enable_if), * std::forward * nulltpr_t * std::chrono? * shared_ptr * unique_ptr. QScopedPointer might be made movable now. New smart pointer session, or on the Mailing list? TODO: We need to test this what is supported with the base line compilers. No for now: std::for_each (issues with leaks) For now, don’t put std lib ABI into Qt ABI, except for nulltpr_t. For lambda’s: how to deal with captures? They are dangerous. Default to capture by value, capture by reference or pointer is problem. We need to be a bit conservative in our public API for now, until we get some more experience. First learn, then slowly introduce. André -- _______________________________________________ Development mailing list Development@qt-project.org http://lists.qt-project.org/mailman/listinfo/development
