Parameter packs and non-deducible template parameters. | Together C & C++ | Page 1

calm willowBOT Mar 28, 2023, 4:54 PM

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void raven Mar 28, 2023, 4:56 PM

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Idk where to even look on cpp reference for this, any explanation is aprecaited

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Here's a proper MRE

enum class Level
    {
        Trace,
        Debug,
        Log,
        Warn,
        Fatal
    };

    void logFormatted(Level, const std::source_location&, std::string);

    template<Level L, class... T>
    struct betterLogger
    {
        betterLogger(
            fmt::format_string<T...> fmt,
            T&&... args,
            const std::source_location location =
                std::source_location::current()
        )
        {
            logFormatted(
                L, location, fmt::vformat(fmt, fmt::make_format_args(args...))
            );
        }
    };
    template<Level L, class... T>
    betterLogger(fmt::format_string<T...>, T&&...) -> betterLogger<L, T...>;

error: deduction guide template contains a template parameter that cannot be deduced
    betterLogger(fmt::format_string<T...>, T&&...) -> betterLogger<L, T...>;
    ^
note: non-deducible template parameter 'L'
    template<Level L, class... T>
                   ^

calm willowBOT Mar 28, 2023, 5:01 PM

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@void raven

Please Do Not Delete Posts!

Please don't delete forum posts. They can be helpful to refer to later and other members can learn from them. In the future you can use !solved to close a post and mark a post as solved.

void raven Mar 28, 2023, 5:02 PM

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hopefully its obvious what I'm trying to do here, however I'm stuck

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@snow zodiac

I tried to do the think you mentioned and I'm not sure how to get the parameter packs working

snow zodiac Mar 28, 2023, 5:16 PM

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I will be online after ~3 hours

void raven Mar 28, 2023, 5:20 PM

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thanks,

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also I figured it out

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this is partial template specification and C++ doesnt have it

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so my origonaly sketchy ~30 line macro was the best way to do it 😄

calm willowBOT Mar 28, 2023, 5:26 PM

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@void raven Has your question been resolved? If so, run !solved :)

void raven Mar 28, 2023, 5:26 PM

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!solved

calm willowBOT Mar 28, 2023, 5:26 PM

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Thank you and let us know if you have any more questions!

This thread is now set to auto-hide after an hour of inactivity

void raven Mar 28, 2023, 5:26 PM

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how the fuck does wheately know when questions are solved

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its kinda creepy ngl

snow zodiac Mar 28, 2023, 5:27 PM

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it's ez - the author of the thread is the last message in the thread, X minutes pass, no other users respond , and thus the bot dumps the message

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at least I assume

#Parameter packs and non-deducible template parameters.