Can I detect whether I've been given a new object as a parameter?

Question

Short Version

For those who don\'t have the time to read my reasoning for this question below:

Is there any way to enforce a policy of "new obje

Answer 1

I can think of a way to do this, but I would definitely not recommend this. Just for argument's sake.

What does it mean for an object to be a "new" object? It means there is only one reference keeping it alive. An "existing" object would have more than one reference to it.

With this in mind, look at the following code:

    class Program
    {
        static void Main(string[] args)
        {
            object o = new object();

            Console.WriteLine(IsExistingObject(o));
            Console.WriteLine(IsExistingObject(new object()));

            o.ToString();  // Just something to simulate further usage of o.  If we didn't do this, in a release build, o would be collected by the GC.Collect call in IsExistingObject. (not in a Debug build)
        }

        public static bool IsExistingObject(object o)
        {
            var oRef = new WeakReference(o);

#if DEBUG 
            o = null; // In Debug, we need to set o to null.  This is not necessary in a release build.
#endif
            GC.Collect();
            GC.WaitForPendingFinalizers();

            return oRef.IsAlive;
        }
    }

This prints True on the first line, False on the second. But again, please do not use this in your code.