[Qt-interest] QList<T> conversion

[Gustavo de Sá Carvalho Honorato]

On Fri, Jan 28, 2011 at 8:56 PM, Thiago Macieira <thiago at kde.org> wrote:
>
> On Friday, 28 de January de 2011 19:58:12 Gustavo de Sį Carvalho Honorato
> wrote:
> > Hi,
> >
> > is it possible to convert QList<A*> to QList<QObject*>, where A inherits
> > from QObject? I would like to do this without create a new QList<QObject*>
> > container and typecasting each element before add into this new one. Is
> > there any better solution than that?
>
> Disclaimer: if you tell anyone I told you this, I'll deny any knowledge of the
> fact.

I've read about reinterpred_cast and I think the reason of your
disclaimer is because the use of reinterpret_cast could be dangerous.
What it's not clear to me is how and which cases reinterpret_cast
could be dangerous. I suppose that in this case it's safe to use
right?

>
>    QList<A *> list;
>    QList<QObject *> objectList  *reinterpret_cast<QList<QObject *>*>(&list);
>
> The data structures in QList<T*> are isomorphic for all T.

What you mean with isomorphic? I understand that this concept is
related to types with same structure or size but different ancestry.
So, I deduced that casting two types with different size is the
problem of using reinterpret_cast. Is it right?

>
> --
> Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
>  Senior Product Manager - Nokia, Qt Development Frameworks
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