Strongly-typed Names for INotifyPropertyChanged

Paul Stovell

Paul Stovell

— 1 min read
This is an old post and doesn't necessarily reflect my current thinking on a topic, and some links or images may not work. The text is preserved here for posterity.

A number of people have asked whether it is possible to implement INotifyPropertyChanged without hard-coding property names as strings inside code.

For example, you would normally write:

public string FirstName
{
    get { return _firstName; }
    set
    {
        _firstName = value;
        OnPropertyChanged(new PropertyChangedEventArgs("FirstName"));
    }
}

Unfortunately the default refactoring tools won't search in string literals, so if LastName was renamed to Surname, you'd need to change the string manually.

One option to enforce compile-time detection would be the following:

public string FirstName
{
    get { return _firstName; }
    set
    {
        _firstName = value;
        OnPropertyChanged(Property.GetFor( () => this.Name ));
    }
}

It could be implemented quite simply with the following static method:

public class Property
{
    public static PropertyChangedEventArgs GetFor(Expression<Func<object>> propertyNameLambda)
    {
        MemberExpression member = propertyNameLambda.Body as MemberExpression;
        if (member != null)
        {
            return new PropertyChangedEventArgs(member.Member.Name);
        }
        return new PropertyChangedEventArgs("");
    }
}

Personally, I don't mind hard-coding property names too much, but it's hardly a best practices, so you may find the above useful. Just beware that it does come with some overhead at runtime.

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