Exotic CRTP pattern for static polymorphism using variadic mixin composition and C++23 explicit object parameters.

This article presents a novel C++23 pattern called "Exotic CRTP" that combines variadic mixin composition with explicit object parameters to achieve static polymorphism with zero runtime overhead. The pattern introduces a `crtp_access` helper that enables compile-time interface dispatch by using `this auto&& self` in base class methods and casting to the derived type, while hiding implementation methods from external callers. The approach is demonstrated through a simple example where a `Base` class calls `implementation()` on a `Derived` class through static dispatch, with the implementation method only accessible through the CRTP access mechanism.

exotic crtp.hpp This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode characters Show hidden characters // Copyright c May 2026 Félix-Olivier Dumas. All rights reserved. // Licensed under the terms described in the LICENSE file // Reference example of the pattern // See: https://medium.com/@felixolivierdumas/exotic-crtp-rethinking-static-polymorphism-with-c-23-89f9e75e8ffd pragma once include <iostream include <type traits include <utility namespace exotic { template<typename... From struct crtp access : From... {}; template<typename T constexpr decltype auto as crtp T&& obj noexcept { using crtp access t = crtp access<std::remove cvref t<T ; return static cast<crtp access t&& obj ; } } struct Base { void interface this auto&& self { return exotic::as crtp self .implementation ; } }; struct Derived : Base { void implementation this exotic::crtp access<Derived self { std::cout << "Derived implementation" << std::endl; } }; int main { Derived d; d.interface ; // perfectly works //d.implementation ; - doesn't work, Derived only shows .interface }