1 /**************************************************************************** 2 ** 3 ** Copyright (C) 2016 The Qt Company Ltd. 4 ** Contact: https://www.qt.io/licensing/ 5 ** 6 ** This file is part of the QtCore module of the Qt Toolkit. 7 ** 8 ** $QT_BEGIN_LICENSE:LGPL$ 9 ** Commercial License Usage 10 ** Licensees holding valid commercial Qt licenses may use this file in 11 ** accordance with the commercial license agreement provided with the 12 ** Software or, alternatively, in accordance with the terms contained in 13 ** a written agreement between you and The Qt Company. For licensing terms 14 ** and conditions see https://www.qt.io/terms-conditions. For further 15 ** information use the contact form at https://www.qt.io/contact-us. 16 ** 17 ** GNU Lesser General Public License Usage 18 ** Alternatively, this file may be used under the terms of the GNU Lesser 19 ** General Public License version 3 as published by the Free Software 20 ** Foundation and appearing in the file LICENSE.LGPL3 included in the 21 ** packaging of this file. Please review the following information to 22 ** ensure the GNU Lesser General Public License version 3 requirements 23 ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. 24 ** 25 ** GNU General Public License Usage 26 ** Alternatively, this file may be used under the terms of the GNU 27 ** General Public License version 2.0 or (at your option) the GNU General 28 ** Public license version 3 or any later version approved by the KDE Free 29 ** Qt Foundation. The licenses are as published by the Free Software 30 ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 31 ** included in the packaging of this file. Please review the following 32 ** information to ensure the GNU General Public License requirements will 33 ** be met: https://www.gnu.org/licenses/gpl-2.0.html and 34 ** https://www.gnu.org/licenses/gpl-3.0.html. 35 ** 36 ** $QT_END_LICENSE$ 37 ** 38 ****************************************************************************/ 39 40 #include "qscopedvaluerollback.h" 41 42 QT_BEGIN_NAMESPACE 43 44 /*! 45 \class QScopedValueRollback 46 \inmodule QtCore 47 \brief The QScopedValueRollback class resets a variable to its previous value on destruction. 48 \since 4.8 49 \ingroup misc 50 51 The QScopedValueRollback class can be used to revert state when an 52 exception is thrown without needing to write try-catch blocks. 53 54 It can also be used to manage variables that are temporarily set, 55 such as reentrancy guards. By using this class, the variable will 56 be reset whether the function is exited normally, exited early by 57 a return statement, or exited by an exception. 58 59 The template can only be instantiated with a type that supports assignment. 60 61 \sa QScopedPointer 62 */ 63 64 /*! 65 \fn template <typename T> QScopedValueRollback<T>::QScopedValueRollback(T &var) 66 67 Stores the previous value of \a var internally, for revert on destruction. 68 */ 69 70 /*! 71 \fn template <typename T> QScopedValueRollback<T>::QScopedValueRollback(T &var, T value) 72 73 Assigns \a value to \ var and stores the previous value of \a var 74 internally, for revert on destruction. 75 76 \since 5.4 77 */ 78 79 /*! 80 \fn template <typename T> QScopedValueRollback<T>::~QScopedValueRollback() 81 82 Assigns the previous value to the managed variable. 83 This is the value at construction time, or at the last call to commit() 84 */ 85 86 /*! 87 \fn template <typename T> void QScopedValueRollback<T>::commit() 88 89 Updates the previous value of the managed variable to its current value. 90 */ 91 92 QT_END_NAMESPACE 93