[Interest] QTextStream doesn't write to QFile

[Bo Thorsen]

Den 16-01-2015 kl. 13:01 skrev Igor Mironchik:
> Hi.
>
> On Fri, 16 Jan 2015 14:44:08 +0300, Koehne Kai
> <Kai.Koehne at theqtcompany.com> wrote:
>
>>
>>> -----Original Message-----
>>> From: interest-bounces+kai.koehne=theqtcompany.com at qt-project.org
>>> [mailto:interest-bounces+kai.koehne=theqtcompany.com at qt-project.org]
>>> On Behalf Of Igor Mironchik
>>> Sent: Friday, January 16, 2015 12:24 PM
>>> To: interest at qt-project.org
>>> Subject: [Interest] QTextStream doesn't write to QFile
>>>
>>> Hi. I'm doing a simple log class. I'm sure that Log creates after
>>> QCoreApplication.
>>> QCoreApplication is static. I create QCoreApplication as:
>>>
>>> static QSharedPointer< QCoreApplication > application(
>>> 	int argc = 0, char ** argv = 0 )
>>> {
>>> 	static QSharedPointer< QCoreApplication > app(
>>> 		new QCoreApplication( argc, argv ) );
>>>
>>> 	return app;
>>> }
>> It seems you're desperately trying here to extend QCoreApplications
>> lifetime as long as possible. This is just asking for trouble: just let
>> QCoreApplication be destructed when your application exits, in main.cpp.
> I'm not desperately trying to extens QCoreApplication lifetime. I need it
> for that reason that Log is singleton and uses QObjects. So Log have to be
> destructed before QCoreApplication.
>
> It's normal practice when using singletons in Qt apps. It works well in
> other my application.

If you want to delete the singletons before the QApplication, call a 
delete on them after exec() returns. The order of static deletes is 
undefined.

It does not work well in any application other than by pure chance.

But why would you think that a QObject can't be deleted after 
QApplication? That works fine, as long as you don't do something else in 
the destructors that use any objects deleted by the QApplication.

One thing you can do to make certain objects are deleted before the qApp 
is to make qApp the parent of the singletons. This also works if 
QApplication is instantiated on the stack.

Bo.

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