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/****************************************************************************
**
** Copyright (C) 2020 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
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** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Free Documentation License Usage
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of
** this file. Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
** $QT_END_LICENSE$
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****************************************************************************/
/*!
\page concurrent-changes-qt6.html
\title Changes to Qt Concurrent
\ingroup changes-qt-5-to-6
\brief Migrate Qt Concurrent to Qt 6.
Qt 6 is a result of the conscious effort to make the framework more
efficient and easy to use.
We try to maintain binary and source compatibility for all the public
APIs in each release. But some changes were inevitable in an effort to
make Qt a better framework.
In this topic we summarize those changes in Qt Concurrent, and provide
guidance to handle them.
\section1 QtConcurrent::run()
QtConcurrent::run() has been improved to work with a variable number
of arguments, so the signatures are changed to:
\code
// run
template <typename T>
QFuture<T> run(Function &&f, Args &&...args)
// run with a QThreadPool argument
template <typename T>
QFuture<T> run(QThreadPool *pool, Function &&f, Args &&...args)
\endcode
As a side effect, if \c f is a pointer to a member function, the first
argument of \c args should be the object for which that member is defined
(or a reference, or a pointer to it). So instead of writing:
\code
QImage image = ...;
QFuture<void> future = QtConcurrent::run(&image, &QImage::invertPixels, QImage::InvertRgba);
\endcode
You have to write:
\code
QFuture<void> future = QtConcurrent::run(&QImage::invertPixels, &image, QImage::InvertRgba);
\endcode
Another side effect is that \c QtConcurrent::run() will not work with
overloaded functions anymore. For example, the code below won't compile:
\include qtconcurrentrun.cpp run-with-overload-calls
Other methods of QtConcurrent have no behavioral changes and do not introduce
source compatibility breaks.
*/
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