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

This class was introduced in Qt 5.0.

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 inherit from QException and implement 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 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

[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; }