ui::Callback< R(Args...) const >¶ Header: winui/core/Callback.hpp. template <typename R, typename... Args> class Callback< R(Args...) const > Derives from std::move_only_function< R(Args...) const >. See the primary template; a const-callable handler, as a const member calls it. Callback¶ Callback() noexcept = default Empty.