io.qt.core.QScopeGuard Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of qtjambi Show documentation
QtJambi base module containing QtCore, QtGui and QtWidgets.
There is a newer version: 6.8.0
/****************************************************************************
**
** Copyright (C) 2009-2024 Dr. Peter Droste, Omix Visualization GmbH & Co. KG. All rights reserved.
**
** This file is part of Qt Jambi.
**
** $BEGIN_LICENSE$
** GNU Lesser General Public License Usage
** This file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
** 
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
** $END_LICENSE$

**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/
package io.qt.core;

import io.qt.QtUninvokable;

/**
 * QScopeGuard is a class of which the sole purpose is to run the function f at the end of a try-with-resource block.
 * This is useful for guaranteeing your cleanup code is executed, whether the function is exited normally, 
 * exited early by a return statement, or exited by an exception.
 * 
 * See QScopeGuard.
 * Example:
 * 
 * QIODevice device = ...

 * try(var guard = new QScopeGuard(device::close)){

 *     if(!device.open())

 *         guard.dismiss();

 *     else

 *         device.write(...);

 * }
 * 
 */
public final class QScopeGuard implements AutoCloseable {
	
	private final QScopedPointer.Data data = new QScopedPointer.Data();
	
	/**
	 * Create a scope guard that will execute function at the end of the scope.
	 * @param function runnable to be executed
	 */
	public QScopeGuard(Runnable function) {
		data.entry = new QScope.RunningEntry(function);
		this.data.cleanable = QtJambi_LibraryUtilities.internal.registerCleaner(this, this.data::cleanup);
	}

	@Override
    @QtUninvokable
	public void close(){
		if(this.data.cleanable!=null) {
			this.data.cleanable.clean();
			this.data.cleanable = null;
		}
	}
	
	/**
	 * Disarms the scope guard, so that the function F will not be called at the end of the scope.
	 */
	@QtUninvokable
	public void dismiss() {
		data.entry = null;
		if(this.data.cleanable!=null) {
			this.data.cleanable.clean();
			this.data.cleanable = null;
		}
	}

    /**
     * The qScopeGuard function can be used to call a function at the end of the scope.
     * See qScopeGuard<T>(F &&f)
     */
	@QtUninvokable
	public static QScopeGuard qScopeGuard(Runnable runnable) {
		return new QScopeGuard(runnable);
	}
}