TypeHints.h

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/*
 * Copyright(c) Sophist Solutions, Inc. 1990-2026.  All rights reserved
 */
#ifndef _Stroika_Foundation_Common_TypeHints_h_
#define _Stroika_Foundation_Common_TypeHints_h_ 1
 
#include "Stroika/Foundation/StroikaPreComp.h"
 
#include <type_traits>
 
#include "Stroika/Foundation/Common/Common.h"
 
/**
 *  \file
 *
 *  \note Code-Status:  <a href="Code-Status.md#Release">Release</a>
 */
 
namespace Stroika::Foundation::Common {
 
    /**
     *  \brief  This is an alias for 'T' - but how we want to pass it on stack as formal parameter.
     *
     *  This is NOT intended to be used very widely, but can be used to decide systematically (by type)
     *  if you should pass a given argument by value or by const reference.
     *
     *  \note   Use sizeof(T) <= 2*sizeof(void*) - because passing by reference involves copying one pointer and then if you
     *          access once, that's a second copy. So may as well copy 2 directly (very loosie goosy, as depends on
     *          relative cost of main memory access versus stack).
     * 
     *  \note   Sadly (from a template use simplicity point of view) - no good way to handle the 'void' case in current C++
     *          (that I'm aware of --LGP 2026-03-19) - so at least give slightly better error message from compiler with requires
     */
    template <typename T, typename CHECK_T = remove_cvref_t<T>>
        requires (not same_as<T, void>)
    using ArgByValueType = conditional_t<(sizeof (CHECK_T) <= 2 * sizeof (void*)) and is_trivially_copyable_v<CHECK_T>, CHECK_T, const CHECK_T&>;
 
}
 
/*
 ********************************************************************************
 ***************************** Implementation Details ***************************
 ********************************************************************************
 */
 
#endif /*_Stroika_Foundation_Common_TypeHints_h_*/