Question

Hi I am doing something related to Reflection, I don’t understand what’s wrong with my code. I try to clean up my codes however, the first piece of code will not update my instance values, when I step through the debugger I can see the correct result from “newobj”, however the “next” reference is lost as a result of not updating my instance values. The only change I have done is to add “this” to queue, to me it is no difference. Can someone explain the reason behind this?

private void UpdateBreathFirst()// This code is WRONG!!! but why?
{
    RootQueue = new Queue<object>();
    RootQueue.Enqueue(this);
    while (RootQueue.Count > 0)
    {
        var next = RootQueue.Dequeue();
        EnqueueChildren(next);

        var newobj = next.GetType().GetMethod("Get").Invoke(next, null);
        ValueAssign(next, newobj);

    }
}



 private void UpdateBreathFirst()//This code produces correct result.
  {
        RootQueue = new Queue<object>();
        var val = GetType().GetMethod("Get").Invoke(this, null);
        ValueAssign(this, val);
        EnqueueChildren(this);
        while (RootQueue.Count > 0)
        {
            var next = RootQueue.Dequeue();
            EnqueueChildren(next);

            var newobj = next.GetType().GetMethod("Get").Invoke(next, null);
            ValueAssign(next, newobj);

        }
    }

Other support codes

private Queue<object> RootQueue;

private void EnqueueChildren(object obj)
{
    if (BaseTypeCompare(obj.GetType(), typeof(SerializedEntity<>)))
    {
        foreach (var propertyInfo in obj.GetType().GetProperties())
        {
            if (BaseTypeCompare(propertyInfo.PropertyType, typeof (List<>)))
            {
                var list = (IList) propertyInfo.GetValue(obj, null);
                if (list != null)
                {
                    foreach (object item in list)
                    {
                        RootQueue.Enqueue(item);
                    }

                }

            }
        }
    }
}

public static void ValueAssign(object a, object b)
{
    foreach (var p in a.GetType().GetProperties())
    {
        foreach (var p2 in b.GetType().GetProperties())
        {
            if (p.Name == p2.Name && BaseTypeCompare(p.GetType(), p2.GetType()))
            {
                p.SetValue(a, p2.GetValue(b, null), null);
            }
        }
    }
}

public static bool BaseTypeCompare(Type t, Type t2)
{
    if (t.FullName.StartsWith(t2.FullName)) return true;
    if (t == typeof(object)) return false;
    return BaseTypeCompare(t.BaseType, t2);
}

Answer 1

I think I found my problem myself, my ValueAssign() has some bug. I found a similar method on the net which works perfectly!

private static void CopyObject(object sourceObject, ref object destObject)
    {
        //  If either the source, or destination is null, return
        if (sourceObject == null || destObject == null)
            return;

        //  Get the type of each object
        Type sourceType = sourceObject.GetType();
        Type targetType = destObject.GetType();

        //  Loop through the source properties
        foreach (PropertyInfo p in sourceType.GetProperties())
        {
            //  Get the matching property in the destination object
            PropertyInfo targetObj = targetType.GetProperty(p.Name);
            //  If there is none, skip
            if (targetObj == null)
                continue;

            //  Set the value in the destination
            targetObj.SetValue(destObject, p.GetValue(sourceObject, null), null);
        }