1. The benefit of bookkeeping is to flatten multiple potential branches of
a switch statement into a subscripting operation. For example if the
booking was a array of std::variant<T&...>(for every element in the tuple)
then to subscript, you just subscript the array.

On Sat, Apr 18, 2026 at 9:26 PM Thiago Macieira via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> On Saturday, 18 April 2026 07:24:12 Pacific Daylight Time Muneem via Std-
> Proposals wrote:
> > 2. What I meant, by "tuples have overhead" is that they have a fixed ABI
> > for all their specaizations, which means that any book keeping has to be
> on
> > the top of the tuple and can't be inside it. Since runtime indexed tuples
> > are a completely different notion than compile indexed tuple since one
> is a
> > product type like a struct. Runtime indexed tuples is heterogeneous
> list. A
> > product type is not a product type if it has anything other than the
> > objects of the multiple types it holds.
>
> And why does it have to be inside, instead of outside? You clearly
> believe
> that to be the case, but you have not proven it or given a basis for why
> it
> should be so. What is the benefit of having the book-keeping at all?
>
> --
> Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
> Principal Engineer - Intel Data Center - Platform & Sys. Eng.
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