std::any, std::optional, and std::variant
The new C++17 data types std::any, std::optional, and std::variant are all based on the Boost libraries
std::any
std::any is a type-safe container for single values of any type which is copy-constructible. There are a few ways to create a std::any container any. You can use the various constructors or the factory function std::make_any. By using any.emplace, you directly construct one value into any. any.reset lets you destroy the contained object. If you want to know whether the container any has a value, use the method any.has_value. You can even get the typeid of the container object via any.type. Thanks to the generic function std::any_cast you have access to the contained object. If you specify the wrong type, you will get a std::bad_any_cast exception.
Here is a code snippet showing the basic usage of std::any.
std::any// any.cpp
...
#include <any>struct MyClass{};
...
std::vector<std::any> anyVec{true, 2017, std...
