I dun a DIP, possibly the best DIP ever

[Steven Schveighoffer]

On 4/24/20 1:16 AM, Simen Kjærås wrote:
> On Friday, 24 April 2020 at 00:16:52 UTC, Manu wrote:
>> On a slightly unrelated note; there's a really interesting idea up-thread
>> about making nested `...` not be expanded by the outer `...`
>> For instance:
>>
>>   template T(A, B...) { ... }
>>   T!(Tup1, Tup2...)...
> 
> I'm wondering if perhaps that's the wrong way around - AliasSeq already 
> does that:
> 
>      T!(Tup1, AliasSeq!Tup2)... // Should only expand Tup1

No, this means:

T!(Tup1[0], AliasSeq!(Tup2[0])), T!(Tup1[1], AliasSeq!(Tup2[1]), ...

> It might be that the more useful behavior is for ...-tuples to be 
> expandable:
> 
>      T!(AliasSeq!(int, char)..., AliasSeq!Tup2)... // Should expand to 
> T!(int, Tup2), T!(char, Tup2)
> 

I think the suggestion quoted by Manu is more useful, we should ignore 
any inner ... when expanding an outer one. This gives maximum 
flexibility. If you want something that's not considered a tuple to be 
considered a tuple, you have the option of declaring it into a tuple 
before the expression. If you want to go the other way (prevent 
expansion of a tuple with ...), without this idea there's no recourse 
(well, you could do a mixin, but that would suck).

-Steve