QException Class

The QException class provides a base class for exceptions that can be transferred across threads. More...

Header:	#include <QException>
CMake:	find_package(Qt6 COMPONENTS Core REQUIRED) target_link_libraries(mytarget PRIVATE Qt6::Core)
qmake:	QT += core
Since:	Qt 5.0
Inherited By:	QUnhandledException

• List of all members, including inherited members

Public Functions

virtual QException *	clone() const
virtual void	raise() const

Detailed Description

Qt Concurrent supports throwing and catching exceptions across thread boundaries, provided that the exception inherits from QException and implements two helper functions:

class MyException : public QException
{
public:
    void raise() const override { throw *this; }
    MyException *clone() const override { return new MyException(*this); }
};

QException subclasses must be thrown by value and caught by reference:

try  {
    QtConcurrent::blockingMap(list, throwFunction); // throwFunction throws MyException
} catch (MyException &e) {
    // handle exception
}

If you throw an exception that is not a subclass of QException, the Qt Concurrent functions will throw a QUnhandledException in the receiver thread.

When using QFuture, transferred exceptions will be thrown when calling the following functions:

• QFuture::waitForFinished()
• QFuture::result()
• QFuture::resultAt()
• QFuture::results()

Member Function Documentation

[virtual] QException *QException::clone() const

In your QException subclass, reimplement clone() like this:

MyException *MyException::clone() const { return new MyException(*this); }

[virtual] void QException::raise() const

In your QException subclass, reimplement raise() like this:

void MyException::raise() const { throw *this; }