Re: Listeners and MVC

"Daniel Pitts" <>
10 Nov 2006 11:28:53 -0800
Jason Cavett wrote:

I have a question about the use of listeners in MVC.

I setup my MVC so that

View has access to Model
Controller has access to View and Model
Model has indirect access to the View via Observer pattern.

What I'm wondering is - why does the Observer pattern even need to be
used? (I'm doing this part from a book I read on MVC.) It seems as
though the Controller can just act as a "pass through" for both because
it has access to both.

So, for example, if I want to open a new file and display a new file I
could do it one of two ways:

With Observer:
1. Fire Event
2. Controller calls Model to read in the file/parse/whatever.
3. Model notifies its Observers and the View (which is one of the
observers) displays the file.

Without Observer:
1. Fire Event
2. Controller calls Model to read in the file/parse/whatever.
3. Once that has happened, Controller calls the View to display the

The only advantage I see to the first way is that I could potentially
create multiple views and the controller would not need to worry about
the view at all. Is this correct? Am I completely off base with how
I'm setting this up? (It seems as though everybody has their own way
of doing MVC which tends to make this confusing.)

Thanks for any help.

Basically, your model firing events is part of the controller. Wiring
up the observables and observers is the controllers job. The view's
job is to render the model whenever it is told to. The models job is to
model the domain, and the controllers job is to manage everything.

Also, keep in mind that MVC does NOT limit you to one model, one view,
and one controller. You can quite easily swap out the view and/or
controller, or have multiple controllers/views for different reasons.

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