Qt 4.8: Exception Class Reference

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- Qt 4.8
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# Exception Class Reference

(QtConcurrent::Exception)

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

Inherited by: QtConcurrent::UnhandledException.

This class was introduced in Qt 4.4.

- List of all members, including inherited members

## 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:

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

## 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; }