CODEWITHSUNDEEP
c#wpfinotifypropertychanged
Thomas Kaemmerling
Thomas Kaemmerling

Reputation: 547

Is it possible to implement Property Changed as Attribute?

I have found an implementation of Propperty Changed Event, where i can Call Property changed without the Name of the Property in the web. And then i have build a Extension Method with it wich is here

public static void OnPropertyChanged(this INotifyPropertyChanged iNotifyPropertyChanged, string    propertyName = null)
{
    if (propertyName == null)
        propertyName = new StackTrace().GetFrame(1).GetMethod().Name.Replace("set_", "");
    FieldInfo field = iNotifyPropertyChanged.GetType().GetField("PropertyChanged", BindingFlags.Instance | BindingFlags.NonPublic);
    if (field == (FieldInfo) null)
        return;
    object obj = field.GetValue((object) iNotifyPropertyChanged);
    if (obj == null)
        return;
    obj.GetType().GetMethod("Invoke").Invoke(obj, new object[2]
    {
        (object) iNotifyPropertyChanged,
        (object) new PropertyChangedEventArgs(propertyName)
    });
}

So i can call Property changed like this:

private bool _foo;
public bool Foo
{
    get { _foo; }
    private set
    {
        _foo = value;
        this.OnPropertyChanged();
    }
}

But I thought, it would be nicer if i don't have to implement the getter and setter of a Property when i use Property changed.

Does anyone now how to implement the OnPropertyChanged Method as Attribute, maybe with AOP?

So that Auto-Property can be used for Property Changed like this:

[OnPropertyChanged]
public bool Foo {set;get;}

Upvotes: 4

Views: 4775

Answers (2)

Thomas Levesque
Thomas Levesque

Reputation: 292455

Check out Fody, and the PropertyChanged add-in. It will modify the IL after compilation to add the code to raise the PropertyChanged event for your properties. It's similar to PostSharp, mentioned in Lasse's answer, but it's free and open-source.

Upvotes: 9

Lasse V. Karlsen
Lasse V. Karlsen

Reputation: 391366

You will need some kind of AOP system to do this.

Either something where you wrap or inherit from your class, and dynamically generate the necessary plumbing in the wrapper/descendant to handle this, or some system like Postsharp that rewrites your code after compilation.

There is nothing built into .NET to handle this.

Upvotes: 4

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