gistfile1.cs

struct Bar
{
	public ushort One;
	public ushort Two;
}

class Foo
{
	private Bar _thing;
	
	public Bar Thing 
	{
		get { return _thing; }
		
		private set
		{
			if (_thing.One == 0 && _thing.Two == 0)
			{
				//locking this is usually bad juju, but it should only happen once
				lock(this)
				{
					if (_thing.One != 0 || _thing.Two != 0)
					{
						return;
					}
					
					_thing = value;
				}
			}
		}
	}
}