[Qt5-feedback] QVariant::toString() and custom types

[Konstantin Ritt]

an ability to convert an arbitrary QVariant to QString only makes not too
much sense. an ability to convert QVariant to an arbitrary type sounds more
useful to me.
i.e.
class A { .. };
class B : public A { .. };
class C : public A { .. };

C c;
QVariant v = qVariantFromValue(c);

// and

Q_ASSERT(v.canConvert<A>());
A a = v.value<A>();

// instead of

Q_ASSERT(v.canConvert<A>() || v.canConvert<B>() || v.canConvert<C>());
A a;
if (v.canConvert<C>()) a = v.value<C>();
else if (v.canConvert<B>()) a = v.value<B>();
else if (v.canConvert<A>()) a = v.value<A>();

BTW, there is a task for this exists at the bug tracker:
http://bugreports.qt.nokia.com/browse/QTBUG-14940

regards,
Konstantin



2011/7/14 Jerome Vizcaino <vizcaino_jerome at yahoo.fr>

> Hi,
>
> I use QVariant a lot in Qt4 to store native but also custom types.
> One thing I find a bit annoying is that there is no way to "extend" the
> toString() QVariant functionnality.
>
> How about adding some sort of operator (à la QDataStream) that custom types
> could provide to help QVariant convert to/from string ?
>
> This would be really convienent in order to easily print QVariant without
> actually knowing if it's custom or native content.
>
> Jérôme
> _______________________________________________
> Qt5-feedback mailing list
> Qt5-feedback at qt.nokia.com
> http://lists.qt.nokia.com/mailman/listinfo/qt5-feedback
>
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