DynamicVariable.java

/* Copyright (C) 2004 - 2008  Versant Inc.  http://www.db4o.com

This file is part of the sharpen open source java to c# translator.

sharpen is free software; you can redistribute it and/or modify it under
the terms of version 2 of the GNU General Public License as published
by the Free Software Foundation and as clarified by db4objects' GPL 
interpretation policy, available at
http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
Suite 350, San Mateo, CA 94403, USA.

sharpen is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
59 Temple Place - Suite 330, Boston, MA  02111-1307, USA. */

/* Copyright (C) 2004 - 2006 Versant Inc. http://www.db4o.com */

package sharpen.core.framework;

public class DynamicVariable<T> {

	public static <T> DynamicVariable<T> newInstance(T initialValue) {
		return new DynamicVariable<T>(initialValue);
	}
	
	private T _value;
	
	public DynamicVariable(T initialValue) {
		_value = initialValue;
	}
	
	public T value() {
		return _value;
	}
	
	public void using(T value, Runnable block) {
		T oldValue = _value;
		_value = value;
		try {
			block.run();
		} finally {
			_value = oldValue;
		}
	}
	
	public <TRESULT> TRESULT using(final T value, final Producer<TRESULT> producer) {
		final ByRef<TRESULT> result = new ByRef<TRESULT>();
		using(value, new Runnable() {
			public void run() {
				result.value = producer.produce();
			}
		});
		return result.value;
	}

}