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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 REQUIRED COMPONENTS Core)
target_link_libraries(mytarget PRIVATE Qt6::Core)
qmake: QT += core
Inherited By:

QUnhandledException

Public Functions

QException()
QException(const QException &other)
virtual ~QException()
virtual QException *clone() const
virtual void raise() const
QException &operator=(const QException &other)

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:

Member Function Documentation

[noexcept] QException::QException()

Constructs a QException object.

[constexpr noexcept] QException::QException(const QException &other)

Creates a copy of other.

Note: Be careful when using this function, as you risk slicing.

See also clone().

[virtual noexcept] QException::~QException()

Destroys this QException object.

[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; }

[noexcept] QException &QException::operator=(const QException &other)

Copy-assigns other over this object.

Note: Be careful when using this function, as you risk slicing.

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