extension method to interface

Question

I am currently using WPF and implementing a model related class deriving INotifyPropertyChanged. I have found that declaring some helper methods is very useful. So I wanted to add these helper methods automatically:

public static class INotifyPropertyChangedHelper
{
    static void notifyPropertyChanged(this INotifyPropertyChanged propertyChanged, string PropertyName = "")
    {
        // errors here
        propertyChanged.PropertyChanged(propertyChanged, new PropertyChangedEventArgs(PropertyName));
    }
    static bool setField<T>(this INotifyPropertyChanged propertyChanged, ref T field, T value, [CallerMemberName]string propertyName = "")
    {
        if (EqualityComparer<T>.Default.Equals(field, value)) return false;
        field = value;
        propertyChanged.notifyPropertyChanged(propertyName);
        return true;
    }
}

Gives me a compiler error

The event 'System.ComponentModel.INotifyPropertyChanged.PropertyChanged' can only appear on the left hand side of += or -=" because PropertyChanged is an event.

Is there an elegant way to solve this problem?

Maybe this will help : http://www.blackwasp.co.uk/INotifyPropertyChangedExt.aspx — Euphoric, Apr 15 '14 at 05:37
This answer might be helpful to you: http://stackoverflow.com/a/4925143/2609288 — Baldrick, Apr 15 '14 at 05:41

score 0 · Accepted Answer · edited May 23 '17 at 11:57

0

No easy trick to do this, extension methods are static methods recognized by compiler which do not become part of class itself. As += and -= on event are accessible only form class defining the event, extension method can't help you there.

I guess you are trying to hack one of the known problems: Implementing INotifyPropertyChanged - does a better way exist?

edited May 23 '17 at 11:57

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answered Apr 15 '14 at 05:56

watbywbarif

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extension method to interface

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