MVP: Is it the View or the Presenter that should know of the Model?

Question

Relatively new to patterns, let me straight away show an example in the context of WinForms.

I have a basic MVP Passive View structure, which one should I go ahead with:

Answer 1

If it's not too much for your introduction to presentation patterns, I'd urge you to take a look at the Presenter-first variant of MVP.

In this variant, and providing an answer to your question, the presenter knows both the model and view but only via interfaces. Neither the view, nor the model know of each other. The presenter co-ordinates each via events and methods.

http://atomicobject.com/pages/presenter+first

http://spin.atomicobject.com/2008/01/30/presenter-first-get-your-triads-talking/

Example:

Class Presenter {
    private IModel model;
    private IView view;

    void Presenter(IModel model, IView view) {
        _model = model;
        _view = view;
    }

    void Initialise() {
        // Attach handler to event view will raise on save
        _view.OnSave += HandleViewSave();
    }

    void HandleViewSave(){
        _model.Save(_view.GetStuffToSave());
    }
}

Very basic example but illustrates the point. The presenter is merely a conduit for communication between the view and model.

Creating the presenter can be done with Poor Man's DI or a proper container:

Presenter p = new Presenter(new CustomerModel(), new CustomerForm());

Note that AtomicObject recommend no reference to presenter, so it actually looks like this:

new Presenter(existingCustomerModel, existingCustomerForm);

existingCustomerModel.Initialise();

The fact that the model and view have scope means the presenter also stays in scope via its references... clever.