Question

I know that there are solutions out there for implementing INotifyPropertyChanged, but none of them are as simple as: reference this library, create/add this attribute, done (I’m thinking Aspect-Oriented Programming here). Does anyone know of a really simple way to do this? Bonus points if the solution is free.

Here are some relevant links (none of which provide a simple enough answer):

• Aspect Examples (INotifyPropertyChanged via aspects)
• LinFu
• INotifyPropertyChanged auto wiring or how to get rid of redundant code
• INotifyPropertyChanged With Unity Interception AOP

Answer 1

Try this
https://github.com/Fody/PropertyChanged

It will weave all properties of types that implement INotifyPropertyChanged and even handles dependencies.

Your Code

public class Person : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    public string GivenNames { get; set; }
    public string FamilyName { get; set; }

    public string FullName
    {
        get
        {
            return string.Format("{0} {1}", GivenNames, FamilyName);
        }
    }

}

What gets compiled

public class Person : INotifyPropertyChanged
{

    public event PropertyChangedEventHandler PropertyChanged;

    private string givenNames;
    public string GivenNames
    {
        get { return givenNames; }
        set
        {
            if (value != givenNames)
            {
                givenNames = value;
                OnPropertyChanged("GivenNames");
                OnPropertyChanged("FullName");
            }
        }
    }

    private string familyName;
    public string FamilyName
    {
        get { return familyName; }
        set 
        {
            if (value != familyName)
            {
                familyName = value;
                OnPropertyChanged("FamilyName");
                OnPropertyChanged("FullName");
            }
        }
    }

    public string FullName
    {
        get
        {
            return string.Format("{0} {1}", GivenNames, FamilyName);
        }
    }    

    public void OnPropertyChanged(string propertyName)
    {
        var propertyChanged = PropertyChanged;
        if (propertyChanged != null)
        {
            propertyChanged(this, new PropertyChangedEventArgs(propertyName));    
        }
    }
}

Or you can use attributes for more fine grained control.