Weak Event seems to fail in test method

Super Lloyd

EDIT this was an accidental post, problem is fixed!! I am running / fixing all my unit test for my home made utilities. I have a weak event build method which look like that

    public static PropertyChangedEventHandler AddWeakHandler<T>(this INotifyPropertyChanged model, T target, Action<T, PropertyChangedEventArgs> action)
        where T : class
    {
        var weakRef = new WeakReference(target);
        PropertyChangedEventHandler handler = null;
        handler = new PropertyChangedEventHandler(
            (s, e) =>
            {
                var strongRef = weakRef.Target as T;
                if (strongRef != null)
                {
                    action(strongRef, e);
                }
                else
                {
                    model.PropertyChanged -= handler;
                    handler = null;
                }
            });
        model.PropertyChanged += handler;
        return handler;
    }

it is used like that (to show that there are no captured variable in the lambda expression

            public object Source
            {
                get { return mSource; }
                set
                {
                    var p = Property;
                    if (p == null)
                        value = null;
                    if (value == mSource)
                        return;

                    if (Source is INotifyPropertyChanged)
                    {
                        ((INotifyPropertyChanged)Source).PropertyChanged -= previous;
                        previous = null;
                    }
                    mSource = value;
                    if (Source is INotifyPropertyChanged)
                    {
                        previous = **WeakEvents.AddWeakHandler**((INotifyPropertyChanged)Source, this, (x, arg) => x.OnSourcePropertyChanged(Source, arg));
                    }
                    if (p != null)
                    {
                        p.OnPropertyChanged();
                    }
                }
            }

I have a simple (XUnit) test looking like that

	\[Fact\]
    public void CheckPropertyPathIsWeakEvent()
	{
		var m = new ModelForPathCheck();
		int n = 0;
		Action<string

Kenneth Haugland

I'm confused. The notification is raised (and usually collected) at the class level. There should be no point in changing the INotifyPreoprtyChanged, but whatever floats your boat I guess.

Super Lloyd

My bad... I should not have posted that!!! Garbage collection worked fine (as test finalizer indicated) but the event was spuriously triggered in the PropertyPath constructor! all solved! ^^

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Super Lloyd

on a side note I didn't understand your confusion! ;P

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Super Lloyd

full source code, for your understanding!

public class PropertyPath<TProp> : PropertyPath
{
internal PropertyPath()
{
}
public new TProp Value
{
get
{
var v = base.Value;
if (v is TProp)
return (TProp)v;
return default(TProp);
}
set { base.Value = value; }
}
}
public class PropertyPath : ModelBase
{
public static PropertyPath<TP> Link<T, TP>(T root, Expression<Func<T, TP>> e, Action<TP> onValueChanged)
{
var pv = new PropertyPath<TP>();
pv.PropertyChanged += (o, eargs) =>
{
if (string.IsNullOrEmpty(eargs.PropertyName) || eargs.PropertyName == "Value")
{
onValueChanged(pv.Value);
}
};
pv.Initialize(e);
pv.Root = root;
return pv;
}
public static PropertyPath<TP> Link<TP>(Expression<Func<TP>> e, Action<TP> onValueChanged)
{
var pv = new PropertyPath<TP>();
pv.PropertyChanged += (o, eargs) =>
{
if (string.IsNullOrEmpty(eargs.PropertyName) || eargs.PropertyName == "Value")
{
onValueChanged(pv.Value);
}
};
pv.Initialize(e);
return pv;
}

    public static PropertyPath<TP> Create<T, TP>(T root, Expression<Func<T, TP>> e)
    {
        var pv = new PropertyPath<TP>();
        pv.Initialize(e);
        pv.Root = root;
        return pv;
    }
    public static PropertyPath<TP> Create<TP>(Expression<Func<TP>> e)
    {
        var pv = new PropertyPath<TP>();
        pv.Initialize(e);
        return pv;
    }

    internal PropertyPath()
    {
    }
    void Initialize(LambdaExpression e)
    {
        object root;
        var path = ReflectionEx.GetLambdaPath(e, out root);
        if (path.Length == 0)
            throw new ArgumentException();
        pvalues = new PropertyValue\[path.Length\];
        roValues = new ReadOnlyCollection<PropertyValue>(pvalues);
        for (int i = 0

Super Lloyd

What you might have misread... the class is NOT registering a listener to its own change! It's listening to change in the source object (!= this!) !!

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Kenneth Haugland

No worries, I just saw the little code snippet and I don't know what your requirements are. My knee jerk reaction was that there has to be a simpler way of doing this. Btw, there is a standard WeakEventManager inside .NET (first intoduced in 3.0) WeakEventManager Class (System.Windows)[^]

Super Lloyd

It's not supported by the PCL!!! But no worries, it's simple enough to implement that I made my own PCL version! :-D

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Kenneth Haugland

PCL?

Super Lloyd

Cross-Platform Development with the Portable Class Library[^] I.e. PCL class library support normal .NET (4.5), UWP, Xamarin iOS, Xamarin Android, and the upcoming .NET Core / .NET native!

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