On Sun, Apr 30, 2023 at 9:26 AM Anoop Rana <ranaanoop986_at_[hidden]> wrote:
>
> @Barry Revzin
>
>> Also why isn't it sufficient to do this:
>>
>> template <typename F, typename... Args>
>> struct C;
>>
>> template <typename... Param, typename Ret, typename... Args>
>> struct C<Ret(*)(Param...), Args...>
>> {
>> C(Ret (*ptrFunc)(const Param&... param), const Args&... args);
>> };
>>
>> Which is valid today?
>
>
>
> I don't think this will work as you expect it to work. Can you give an example of a working demo where the template arguments are deduced from constructor arguments/parameters using CTAD. For example something like C c(somefunctionname, 5,5); where we don't have to specify the arguments when creating an instance. The point is that they should be deduced from constructor arguments using CTAD

As I mentioned, you need a template deduction guide to make it work.
Like this https://gcc.godbolt.org/z/Mz57vj7Ps

template <typename... Param, typename Ret, typename... Args>
C(Ret(*ptr)(Param...), Args...) -> C<decltype(ptr), Args...>;