QException Class | Qt Core 5.6

Qt 5.6 | Qt Core | C++ Classes | QException

Qt 5.6.2 Reference Documentation

# QException Class

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

Header: | #include <QException>
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

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

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

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