[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;
}
But this Log doesn't write anything to the file. File creates, I'm sure in
it. But nothing writes. What is the reason?
And another problem is that QFile in destructor crashes application. Why?
---
//! Severity
enum Severity {
//! Info.
Info = 0,
//! Warning.
Warning = 1,
//! Error.
Error = 2,
//! Critical.
Critical = 3
}; // enum Severity
//
// Log
//
class LogPrivate;
//! Log.
class Log {
public:
static Log instance();
Log operator [] ( Severity s );
Log operator ( const QString data );
Log operator ( const char * data );
private:
Log();
~Log();
private:
Q_DISABLE_COPY( Log )
QScopedPointer LogPrivate d;
}; // class Log
#define LOG( S ) Log::instance()[ S ]
---
And here is implementation:
---
//
// LogPrivate
//
class LogPrivate {
public:
LogPrivate()
: severity( Info )
{
stream.setCodec( QTextCodec::codecForName( UTF-8 ) );
}
~LogPrivate()
{
stream.flush();
if( file.isOpen() ) // HERE APPLICATION CRASHES !!!
file.close(); }
void initLogFile( const QDate d )
{
if( date != d )
{
stream.flush();
if( file.isOpen() )
file.close();
file.setFileName( QLatin1String( ./log/test. ) +
d.toString( QLatin1String( yy.MM.dd ) ) +
QLatin1String( .log ) );
file.open( QIODevice::WriteOnly | QIODevice::Append );
stream.setDevice( file );
date = d;
}
}
QString severityToString() const
{
switch( severity )
{
case Info :
return QLatin1String( info );
case Warning :
return QLatin1String( warning );
case Error :
return QLatin1String( error );
case Critical :
return QLatin1String( critical );
default :
return QString();
}
}
//! Severity.
Severity severity;
//! Stream.
QTextStream stream;
//! File.
QFile file;
//! Date.
QDate date;
}; // class LogPrivate
//
// Log
//
Log
Log::instance()
{
static Log log;
return log;
}
Log
Log::operator [] ( Severity s )
{
d-severity = s;
d-initLogFile( QDate::currentDate() );
d-stream \n [ QTime::currentTime().toString(
QLatin1String(
hh:mm:ss ) )
] [ d-severityToString() ] ;
d-severity = Info;
return *this;
}
Log
Log::operator ( const QString data )
{
d-stream data;
return *this;
}
Log
Log::operator ( const char * data )
{
Log::operator ( QString( data ) );
return *this;
}
Log::Log()
: d( new LogPrivate )
{
}
Log::~Log()
{
}
---
--
Best Regards,
Igor Mironchik.
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Re: [Interest] QTextStream doesn't write to QFile
Den 16-01-2015 kl. 13:01 skrev Igor Mironchik:
Hi.
On Fri, 16 Jan 2015 14:44:08 +0300, Koehne Kai
kai.koe...@theqtcompany.com wrote:
-Original Message-
From: interest-bounces+kai.koehne=theqtcompany@qt-project.org
[mailto:interest-bounces+kai.koehne=theqtcompany@qt-project.org]
On Behalf Of Igor Mironchik
Sent: Friday, January 16, 2015 12:24 PM
To: interest@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.
--
Viking Software
Qt and C++ developers for hire
http://www.vikingsoft.eu
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Re: [Interest] QTextStream doesn't write to QFile
On Fri, 16 Jan 2015 15:25:44 +0300, Bo Thorsen b...@vikingsoft.eu wrote:
Den 16-01-2015 kl. 13:01 skrev Igor Mironchik:
Hi.
On Fri, 16 Jan 2015 14:44:08 +0300, Koehne Kai
kai.koe...@theqtcompany.com wrote:
-Original Message-
From: interest-bounces+kai.koehne=theqtcompany@qt-project.org
[mailto:interest-bounces+kai.koehne=theqtcompany@qt-project.org]
On Behalf Of Igor Mironchik
Sent: Friday, January 16, 2015 12:24 PM
To: interest@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.
Few years ago in this list Nils Jeisecke wrote to me that QWidget's
destructor needs QApplication instance. So I think that QObject's
destructor needs QCoreApplication.
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.
Thank you for your suggestions.
--
Best Regards,
Igor Mironchik.
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