PropertyInfo.SetterCalled event

[Ramobo]

Dependency properties require a lot of boilerplate, and they're not generic:

public class FancyButton : Button
{
    public static readonly DependencyProperty CornerRadiusProperty = DependencyProperty.Register(nameof(CornerRadius), typeof(CornerRadius), typeof(FancyButton));

    public CornerRadius CornerRadius
    {
        get => (CornerRadius)GetValue(CornerRadiusProperty);

        set
        {
            SetValue(CornerRadiusProperty, value);
        }
    }
}

IL weaving-based generators don't work with statically checked stuff like {TemplateBinding}, and often don't support read-only or non-auto properties.

What about a PropertyInfo.SetterCalled event that obsoletes dependency properties for the most common use cases?

public class FancyButton : Button
{
    // The property system uses `PropertyInfo.*` to find out everything that it wants to know, and `PropertyInfo.SetterCalled` to get notified of potential value changes.
    public CornerRadius { get; set; }
}

11 lines turned into 1.

As far as I can tell, the only things that this event wouldn't support are:

• Coercion and validation.
• Attached properties.

In these cases, you'd just define a dependency property as usual.