Cpp

I often see perfect forwarding listed for constructor arguments, but not usually for functions with a return or methods. Here is my solution for an method method of class Cls:

template<typename ...Args>
static auto method(Cls* cls, Args &&  ...args)
  -> typename std::result_of<decltype(&Cls::method)(Cls, Args...)>::type {
    return cls->method(std::forward<Args>(args)...);
}

This is useful if you want to call protected classes from a “helper” friend class, for example, to expose them to tests without having to require GoogleTest/GoogleMock to be available for regular users.

The every-three-year cycle has changed the development of C++; we are now getting consistent releases somewhere in-between the major and minor releases of old. The 2017 release may be called minor by some, with a huge portion of the planned improvements being pushed back another 3-6 years, but there were several substantial changes in useful areas; it is much more impactful than C++14, for example. This almost feels like a lead-in release to C++20.

The std::variant, std::optional, and std::any additions to the standard library are huge, and can restructure the way you program (and are available for older C++ releases through Boost and other libraries).

Unlike C++11, this is a minor release, focused mostly on improvements on top of C++11 changes, with very little that one could call “new”. C++14 feels a little more natural than C++11 by expanding the usage of features and implementing common sense additions that were missed in the original C++11 release. There were also quite a few bug fixes; several of these were backported into C++11 mode in compilers.

Also, while C++11 is always available in ROOT 6, C++14 requires a flag and compatible compiler, so C++14 features are often unavailable. The Conda-Forge ROOT package has C++17 enabled.

C++11 was the largest change ever made to C++; and due to the changed release schedule, probably will remain the largest single change. It is a well thought out, mostly backward-compatible change that can cause you to completely rethink the way you write code in C++. It is best thought of as almost a new language, a sort of (C++)++ language. There are too many changes to list here, and there are excellent resources available, so this is meant to just give you a taste of some of the most useful changes.

Many of the features work best together, or are related. There already are great resources for learning about C++11 (listed at the bottom of this lesson), and C++11 is already in use in most software. Therefore, the remainder of this lesson will cover a few of the common idioms in C++11 that a programmer experienced with the older C++ might not immediately think of.