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

> Source: <https://gist.github.com/unrays/4eae18cf6a6e46e83c071fdaa1d03205>
> Published: 2026-05-22 20:00:44+00:00

exotic_crtp.hpp

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// 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()

}