Question

I’m looking for an easy way to enforce the correct implementation of INotifyPropertyChanged i.e. when PropertyChanged is raised it must reference a property that is actually defined. I tried doing this with the new CodeContract tools from Microsoft, but I keep getting the warning “CodeContracts: requires unproven”. Here is my code…

public sealed class MyClass : INotifyPropertyChanged
{
    private int myProperty;
    public int MyProperty
    {
        get
        {
            return myProperty;
        }
        set
        {
            if (myProperty == value)
            {
                return;
            }

            myProperty = value;
            OnPropertyChanged("MyProperty");
        }
    }

    private void OnPropertyChanged(string propertyName)
    {
        Contract.Requires(GetType().GetProperties().Any(x => x.Name == propertyName));

        var handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

Is there anyway to get this to work?

Answer 1

I assume you mean with the static analysis tools? (I would expect the runtime check to work, at least – and you could presumably leave it in debug builds). I doubt that this is something that static analysis is going to be able to see through – GetType().GetProperties() is simply too complex, etc.

In short; I doubt it… lambdas (Expression) are an option, but they are much slower than passing just a string.