[Interest] QVariant cannot take custom type

[Aekold Helbrass]

Complete QtCreator project in attachment. I'm running it on QtCreator 2.7.0
and Qt 5.0.1, SUSE Linux 12.3.


On Fri, Apr 5, 2013 at 2:30 PM, Pritam Ghanghas <Pritam_Ghanghas at infosys.com
> wrote:

> can you send compilable code that reproduces this problem. I will try here.
> ________________________________
> From: interest-bounces+pritam_ghanghas=infosys.com at qt-project.org[interest-bounces+pritam_ghanghas=
> infosys.com at qt-project.org] on behalf of Aekold Helbrass [
> helbrass at gmail.com]
> Sent: Friday, April 05, 2013 4:45 PM
> To: Qt-interest Interest
> Subject: Re: [Interest] QVariant cannot take custom type
>
> Ok, I've tried this one:
>
>         QVariant var(QMetaType::QObjectStar, &item);
>
>
> and it almost works. Pointer somehow gets crippled after using
> QMetaProperty.write. When Item* is created originally - address is
> 0x1b952fo. But into Holder it is written as 0x1b95480.
>
> Is is even possible? Maybe I'm constructing QMetaProperty not as
> intended?...
>
>
> On Fri, Apr 5, 2013 at 2:00 PM, Pritam Ghanghas <
> Pritam_Ghanghas at infosys.com<mailto:Pritam_Ghanghas at infosys.com>> wrote:
> use gdb and see where exactly it segfaults. That will give better pointers
> than random guesses.
> You can try posting backtrace here.
> ________________________________
> From: interest-bounces+pritam_ghanghas=infosys.com at qt-project.org<mailto:
> infosys.com at qt-project.org> [interest-bounces+pritam_ghanghas=
> infosys.com at qt-project.org<mailto:infosys.com at qt-project.org>] on behalf
> of Aekold Helbrass [helbrass at gmail.com<mailto:helbrass at gmail.com>]
> Sent: Friday, April 05, 2013 4:15 PM
> To: Conti Manuele
> Cc: Qt-interest Interest
> Subject: Re: [Interest] QVariant cannot take custom type
>
> Thanx, that one was close, but still segfault:
>
>         QSharedPointer<Item> pointer(item);
>
>         QVariant var = QVariant::fromValue(pointer);
>
>         list.append(var);
>
>
>
> On Fri, Apr 5, 2013 at 1:33 PM, Conti Manuele <conti.ma at alice.it<mailto:
> conti.ma at alice.it><mailto:conti.ma at alice.it<mailto:conti.ma at alice.it>>>
> wrote:
> Hi All,
> There is a problem in your code, actually I use this and work perfectly:
> Q_DECLARE_METATYPE(QSharedPointer<QPlcServerSocket::QExternalCommand>)
> qRegisterMetaType< QSharedPointer<QPlcServerSocket::QExternalCommand> >();
>
>
> Bye
>
> On 04/05/2013 12:27 PM, Samuel Gaist wrote:
> > He explains how to handle QObject * so a pointer to QObject instance,
> not a QObject instance.
> >
> > On 5 avr. 2013, at 12:22, Aekold Helbrass wrote:
> >
> >> So, it is absolutely impossible to use QObject-derived class with
> QVariant? I'm storing QList of pointers already, and I want to write that
> with QMetaProperty. The only thing that needs copy-constructor, in my
> understanding, is qRegisterMetaType invocation.
> >>
> >> I even read an article where guy explains how to get other types than
> one you're storing, so it looks like there is no problem in storing QObject
> in QVariant, but for some reason it doesn't work for me:
> >>
> http://steveire.wordpress.com/2011/03/16/implementing-qvariantqmetatype-features-with-template-tricks/
> >>
> >>
> >> On Fri, Apr 5, 2013 at 12:44 PM, André Somers <andre at familiesomers.nl
> <mailto:andre at familiesomers.nl><mailto:andre at familiesomers.nl<mailto:
> andre at familiesomers.nl>>> wrote:
> >> Op 5-4-2013 11:39, Sven Bergner schreef:
> >>> Hello,
> >>> you can use a custom type with QVariant by declaring it
> >>> using Q_DECLARE_METATYPE ( Type ).
> >>> Hope that helps.
> >>>
> >> It does not. That was already in the code posted in the opening post. As
> >> noted by others, the issue lies with trying to use a QObject derived
> >> class here.
> >>
> >> André
> >>
> >> --
> >> You like Qt?
> >> I am looking for collegues to join me at i-Optics!
> >>
> >> _______________________________________________
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> >>
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