[Development] QHash for Qt 6

[Ville Voutilainen]

On Fri, 20 Dec 2019 at 15:48, Giuseppe D'Angelo via Development
<development at qt-project.org> wrote:
>
> Il 20/12/19 12:20, Philippe ha scritto:
> > std::unordered_map is before all an interface and the implemenation varies according to the library supplier.
> > And this, potentially much more eg. than std::vector.
> > And X-Platorm Qt users would expect performance consistency I guess.
>
> Devil's advocate, again: this also applies, say, to std algorithms. Or
> operator new. Should we stop using them and roll our own?

Do you expect to be able to write a significantly better
std::for_each? find_if? sort?
For operator new.. well, we already replace it with a better one in
some cases. If we could
eat the cost, we might seriously consider allocators, too.

> > And that's the whole point of Lars' proposal.
> And my point was that Qt shouldn't _really_ bother reinventing something
> already easily available elsewhere. Usage of a "fast hash" internally to
> Qt doesn't mean we provide that API to our user (hello, QFlatMap; or
> std::vector usages all over Qt internals.).

Well, in this case, we are providing the same API as before, but with
a better implementation.