Question

I was reading the source code of MvvmLight, and I’ve seen this function in ViewModelBase.cs:

protected virtual void RaisePropertyChanged(string propertyName)
{
    PropertyChangedEventHandler changedEventHandler = this.PropertyChanged;
    if (changedEventHandler == null)
        return;
    changedEventHandler((object) this, new PropertyChangedEventArgs(propertyName));
}

I don’t see why there is a cast here, but because this function is critical in MvvmLight, I’m guessing there is an advantage of doing so…

Answer 1

If you’re looking at the code through Reflector you’ll always see strange stuff like this because Visual Studio lets you take short-cuts that the compiler works out for you, like passing a type as object without casting it to object.

But to answer your question, the eventhandler requires an object, so it passes this as (object)