This is universal template parameters, p1985, and p2989, together with
Barry's paper.

On Tue, Nov 14, 2023, 17:41 Frederick Virchanza Gotham via Std-Proposals <
std-proposals_at_[hidden]> wrote:

>
> Copying the author of P1858 on this email.
>
> Barry, in your paper you propose that a tuple type, for example:
>
> typedef std::tuple<int, char, float> MyTupleType;
>
> could be turned into a parameter pack with the following syntax:
>
> MyTuple::[:]
>
> Had you considered providing a language feature that would get you _all_
> of the template parameters, including the constants? Let's say the syntax
> for this would be:
>
> MyTuple+
>
> So for example consider the following code snippet:
>
> template<int i, int j, int k, typename A> class SomeClass1 { /*
> constructor needed in here */ };
> template<int i, int j, int k, typename A> class SomeClass2 {};
>
> typedef SomeClass2<4,5,6,long> Monkey;
>
> auto &Func(Monkey const &arg)
> {
> static SomeClass1< Monkey+ > obj(arg);
> return obj;
> }
>
> So here 'Monkey+' would expand to:
>
> int, int, int, typename
>
> I suppose this would have to be a new kind of hybrid parameter pack
> (hybrid meaning it contains both constants and types).
>
>
> On Sunday, November 12, 2023, Bjorn Reese via Std-Proposals <
> std-proposals_at_[hidden]> wrote:
>
>> On 11/12/23 18:15, Frederick Virchanza Gotham via Std-Proposals wrote:
>>
>> The operator, typename+ , turns a tuple into a parameter pack. Or it can
>>> turn a variant into a parameter pack. Or any template class into a
>>> parameter pack.
>>>
>>
>> Already covered by P1858, section 4.
>>
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