[Development] QAbstractItemModel::createIndex(void const*)?

Matthew Woehlke mwoehlke.floss at gmail.com
Tue Nov 27 20:59:01 CET 2018

On 27/11/2018 12.46, Konstantin Shegunov wrote:
> On Tue, Nov 27, 2018 at 7:41 PM Matthew Woehlke wrote:
>> Is there any reason not to add [createIndex(int, int, void const*)]?
> I'd say the question is rather, is there really a reason to add one?

Well, in my project, I did (add the overload to my own model). Requiring
the caller to explicitly cast is annoying, and I don't see any benefit.

> Usually the data is contained in a non-const object, presumably in the
> model itself, so the pointer isn't ordinarily pointing to an immutable
> object.

Right. Mostly. Note that in my original example, I was supplying a
pointer to a member of my model. Because index() is const, when I take
that address, I get a const pointer, even though the member itself isn't
const (and it would be okay for me to cast it to non-const when using it
in a non-const member).

It sounds like Jean-Michaƫl ran into the exact same problem.

> Do you need to enforce the const?

In my case, no, and anyway it would be up to the user to DTRT if they
pass a pointer to an object that is actually immutable.

The point is, the pointer is going to be coerced into a quintptr anyway,
so there is no particular reason why we *shouldn't* accept a const
pointer as the data... not having that overload just forces the user to
explicitly recast the pointer themselves.


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