Qt Reference Documentation

Exception Class Reference

(QtConcurrent::Exception)

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

 #include <QtCore>

Inherited by QtConcurrent::UnhandledException.

This class was introduced in Qt 4.4.

Public Functions

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

Detailed Description

The Exception 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 QtConcurrent::Exception and implement two helper functions:

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

QtConcurrent::Exception 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 QtConcurrent::Exception, the Qt Concurrent functions will throw a QtConcurrent::UnhandledException in the receiver thread.

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

Member Function Documentation

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

In your QtConcurrent::Exception subclass, reimplement clone() like this:

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

void Exception::raise () const [virtual]

In your QtConcurrent::Exception subclass, reimplement raise() like this:

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