[Development] QOptional

[André Somers]

Thiago Macieira schreef op 21-8-2014 16:14:
> On Thursday 21 August 2014 11:15:01 Julien Blanc wrote:
>> Do you mean that you would change QSqlRecord::value to return, instead
>> of a QVariant that can be null, a QVariant holding either an optional or
>> a non-optional object ? I don’t see any advantages in doing so. That
>> would make sense if you could get rid of the whole QVariant stuff, but
>> that would imho need a complete redesign of QtSql. Otherwise, it’ll just
>> add an extra layer, not providing any usefull feature (QVariant already
>> does the job quite well in providing the nullability feature).
> That's exactly what I am asking for. I'd like to deprecate QVariant's internal
> nullability concept and make it rely on carrying a QOptional for a type to be
> null.
>
> If we don't do that, then QVariant: of a QOptional<QString> could be:
>
>   1) a null QVariant
>   2) a non-null QVariant containing a null (disengaged) QOptional
>   3) a non-null QVariant containing a non-null (engaged) null QString
>   4) a non-null QVariant containing a non-null (engaged) non-null QString
>
> That's just non-sense and confusing to me. I'd like to collapse 1-3 as much as
> possible.
I assume you also want to remove the nullability of QString then?
In both cases, you're going to break *a lot* of code.

André