Question

I’m creating an app that allows users to create, list and edit customers.

Would you create a separate view models for listing entites; adding updating deleting entites or one viewmodel with an enumeration passed to establish functionality?

Answer 1

I would create a separate viewModel for each functionality.

In general I dislike to have an enumeration to establish functionality; it force you to have many “if” in your code, that becomes complex and difficult to understand. In each context I try to avoid this using different technique depending on the context: ViewModels in the application layer of a WPF application, the State pattern when the different behaviour is dependant from some sort of state, the Strategy pattern when I have to inject the behaviour at runtime or I have to reutilize the behaviour in different classes, and so on …
Sometimes you need to mix this technique: for example you can have a ViewModel to edit customer that has a complex behaviour implemented by a state machine.