working main.cpp is attached. I am not sure why you want to do this.
________________________________
From: Aekold Helbrass [[email protected]]
Sent: Friday, April 05, 2013 5:59 PM
To: Pritam Ghanghas
Cc: Qt-interest Interest
Subject: Re: [Interest] QVariant cannot take custom type
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
<[email protected]<mailto:[email protected]>> wrote:
can you send compilable code that reproduces this problem. I will try here.
________________________________
From:
[email protected]<mailto:[email protected]>
[[email protected]<mailto:[email protected]>]
on behalf of Aekold Helbrass [[email protected]<mailto:[email protected]>]
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
<[email protected]<mailto:[email protected]><mailto:[email protected]<mailto:[email protected]>>>
wrote:
use gdb and see where exactly it segfaults. That will give better pointers than
random guesses.
You can try posting backtrace here.
________________________________
From:
[email protected]<mailto:[email protected]><mailto:[email protected]<mailto:[email protected]>>
[[email protected]<mailto:[email protected]><mailto:[email protected]<mailto:[email protected]>>]
on behalf of Aekold Helbrass
[[email protected]<mailto:[email protected]><mailto:[email protected]<mailto:[email protected]>>]
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
<[email protected]<mailto:[email protected]><mailto:[email protected]<mailto:[email protected]>><mailto:[email protected]<mailto:[email protected]><mailto:[email protected]<mailto:[email protected]>>>>
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
>> <[email protected]<mailto:[email protected]><mailto:[email protected]<mailto:[email protected]>><mailto:[email protected]<mailto:[email protected]><mailto:[email protected]<mailto:[email protected]>>>>
>> 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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#include <QCoreApplication>
#include <QObject>
#include <QList>
#include <QMetaType>
#include <QMetaObject>
#include <QMetaProperty>
#include <QDebug>
#include <QSharedPointer>
#include <QVariant>
#include "item.h"
#include "holder.h"
Q_DECLARE_METATYPE(Item)
Q_DECLARE_METATYPE(Item*)
Q_DECLARE_METATYPE(Holder)
Q_DECLARE_METATYPE(QList<Item*>)
Q_DECLARE_METATYPE(QSharedPointer<Item>)
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
int typeItem = qRegisterMetaType<Item>("Item");
int typeHolder = qRegisterMetaType<Holder>("Holder");
int typeItemList = qRegisterMetaType<QList<Item*> >("QList<Item*>>");
int typeItemPointer = qRegisterMetaType<Item*>("Item*");
int typePointer = qRegisterMetaType<QSharedPointer<Item*> >("QSharedPointer<Item>");
QList<Item*> list;
for (int i = 0; i < 10; i++) {
void* created = QMetaType::create(typeItem);
Item* item = static_cast<Item*>(created);
item->setName("item " + QString::number(i));
qDebug() << item->name();
// attempt 1:
//QVariant var(typeItem, created);
// attempt 2:
//QVariant var;
//var.setValue(item);
// attempt 3:
//QVariant var = QVariant::fromValue(item);
//QVariant var = qVariantFromValue((void*)created);
//void* extracted = var.value<void*>();
//Item* it2 = var.value<Item*>();
//QSharedPointer<Item> pointer(item);
//QVariant var = QVariant::fromValue(pointer);
// QVariant var(QMetaType::QObjectStar, item);
// Item* it2 = var.value<Item*>();
//QVariant var(QMetaType::VoidStar, &created);
list.append(item);
}
Holder* holder = new Holder();
int index = holder->metaObject()->indexOfProperty("items");
QMetaProperty property = holder->metaObject()->property(index);
QVariant var = QVariant::fromValue(list);
property.write(holder, var);
QList<Item*> items = holder->items();
for (int i = 0; i < items.size(); i++) {
Item* item = items.at(i);
qDebug() << "name: " << item->name();
}
return a.exec();
}
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