While I was doing research for my book and blog posts about C++17 several times I stumbled upon this pattern for visitation of std::variant:
template<class... Ts> struct overload : Ts... { using Ts::operator()...; };
template<class... Ts> overload(Ts...) -> overload<Ts...>;
std::variant<int, float> intFloat { 0.0f };
std::visit(overload(
[](const int& i) { ... },
[](const float& f) { ... },
),
intFloat;
);With the above pattern, you can provide separate lambdas “in-place” for visitation.
It’s just two lines of compact C++ code, but it packs a few interesting concepts.
Let’s see how this thing works and go through the three new C++17 features that enable this one by one.
