Question

I just recently discovered an INotifyPropertyChange interface. I managed to implement this interface in my clss and everything works fine. However I was wondering if it is possible to intercept this event in code and fire a function
Let’s say that I have a function

DoStuff()

and I wan’t to fire this function everytime property1, property2 or property3 changes.
Of course I could put this function in set block in my class but this is not a good idea(I think).

Answer 1

If you mean to internal method that’ll handle this event you can do it by registering to the event in the class constructor. For example:

public class AnswerViewModel : IAnswerViewModel
{
    public event PropertyChangedEventHandler PropertyChanged;

    private string content;

    public AnswerViewModel()
    {
        PropertyChanged += (sender, args) => DoStuff();
    }

    public string Content
    {
        get { return content; }
        set
        {
            content = value;
            PropertyChanged(this, new PropertyChangedEventArgs("Content"));
        }
    }

    public void DoStuff()
    {
        // this method will be called whenever PropertyChanged event raised
    }
}

If the intercepting method belongs to other class:

public class PropertiesInterceptor
{
    private readonly AnswerViewModel viewModel;

    private readonly List<string> propertiesToIntercept =
        new List<string> { "property1", "property2", "property3" };

    public PropertiesInterceptor(AnswerViewModel viewModel)
    {
        this.viewModel = viewModel;
        viewModel.PropertyChanged += OnPropertyChanged;
    }

    private void OnPropertyChanged(object sender, PropertyChangedEventArgs args)
    {
        if (propertiesToIntercept.Contains(args.PropertyName))
        {
            DoStuff();
        }
    }

    private void DoStuff()
    {
        // Do something with viewModel
    }
}