Badge.h

Go to the documentation of this file.

/** @noop License Comment
 *  @file
 *  @copyright
 *  This Source Code is subject to the terms of the Mozilla Public License, v2.0.
 *  If a copy of the MPL was not distributed with this file You can obtain one at
 *  https://mozilla.org/MPL/2.0/
 *  
 *  @author David Mórász
 *  @date 2025
 */
 
#pragma once
 
namespace Mcro::Badge
{
    /**
     * Use this template to give exclusive access to functions to specific classes, like so:
     * class A;
     * class B;
     * class C;
     * 
     * class A
     * {
     *     static void CallFromB(TBadge<B> badge) {...}
     * };
     *
     * class B
     * {
     *     void Foobar()
     *     {
     *         // OK
     *         A::CallFromB({});
     *     }
     * };
     *
     * class C
     * {
     *     void Foobar()
     *     {
     *         // compile error:
     *         // badge template instance declared in A::CallFromB is only friends with class B,
     *         // therefore the private default constructor is inaccessible from class C
     *         A::CallFromB({});
     *     }
     * };
     */
    template<class T>
    class TBadge
    {
        friend T;
    private: TBadge() {}
    };
}
 
template <typename T>
using TBadge = Mcro::Badge::TBadge<T>;