Switch-Case on Class.PropertyName (not value)

Question

I have a class which implements INotifyPropertyChanged like this:

public class Person : INotifyPropertyChanged {

    public event PropertyChangedEv         


        

Answer 1

You can use Expression> to do what you want.

Define this method:

private string ToPropertyName(Expression> @this)
{
    var @return = string.Empty;
    if (@this != null)
    {
        var memberExpression = @this.Body as MemberExpression;
        if (memberExpression != null)
        {
            @return = memberExpression.Member.Name;
        }
    }
    return @return;
}

Then you can write this:

void Person_PropertyChanged(object sender, PropertyChangedEventArgs e){
    switch (e.PropertyName)
    {
        case ToPropertyName(() => Person.Color);
            //some stuff
            break;
        default:
            break;
    }
}

Now you have some strongly-typed joy. :-)

---

To get switch-like functionality without switch and messy if/then/else you can do this:

void Person_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
    var @switch = new Dictionary()
    {
        { ToPropertyName(() => Person.Color), () => { /* some stuff */ } },
        { ToPropertyName(() => Person.Size), () => { /* some other stuff */ } },
        { ToPropertyName(() => Person.Shape), () => { /* some more stuff */ } },
    };

    if (@switch.ContainsKey(e.PropertyName))
    {
        @switch[e.PropertyName]();
    }
    else
    {
        /* default stuff */
    }
}