Introduce QScopeGuard

A RAII style class which calls a function at end of scope.

Example usage:
    auto cleanup = qScopeGuard([] { <my cleanup code> ; });

[ChangeLog][QtCore] Introduced QScopeGuard.

Task-number: QTBUG-62894
Change-Id: Ife67f5c76255a1fafbae03367263da0bac9a0070
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 67 insertions, 0 deletions

diff --git a/src/corelib/doc/snippets/code/src_corelib_tools_qscopeguard.cpp b/src/corelib/doc/snippets/code/src_corelib_tools_qscopeguard.cpp
new file mode 100644
index 0000000000..c8c5f694c6
--- /dev/null
+++ b/src/corelib/doc/snippets/code/src_corelib_tools_qscopeguard.cpp
@@ -0,0 +1,67 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Sérgio Martins <sergio.martins@kdab.com>
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** 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.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+//! [0]
+void myComplexCodeWithMultipleReturnPoints(int v)
+{
+    // The lambda will be executed right before your function returns
+    auto cleanup = qScopeGuard([] { code you want executed goes HERE; });
+
+    if (v == -1)
+        return;
+
+    int v2 = code_that_might_through_exceptions();
+
+    if (v2 == -1)
+        return;
+
+    (...)
+}
+//! [0]