Re: Beginner NSAlert question

FROM : Paul Bruneau
DATE : Wed Nov 07 17:14:35 2007

On Nov 6, 2007, at 4:50 PM, David Spooner wrote:

> On 6-Nov-07, at 9:25 AM, Keary Suska wrote:
>

>> on 11/6/07 10:29 AM, <email_removed> purportedly said:
>>

>>> In the middle of this -complete code, an alert might be required. Do
>>> I put the alert code in the orderStep class, or in the controller
>>> class?

>>
>> This may be a gray area of MVC, but I don't see a problem assuming 
>> that the
>> NSAlert class is the controller class in this situation, and the 
>> model is
>> simply asking the controller to prompt for information.

>
> In my opinion, a model object should have no knowledge of any 
> associated controller(s).  Any information required by a model's 
> manipulation methods should be either supplied as arguments, 
> available through a delegate, or implicit in the model itself.  It 
> is the controller's responsibility to prompt for such information 
> where necessary.  The only communication from model to controller 
> should occur through key/value observation.  This discipline is 
> particularly useful when providing multiple views of a model.
>
> I would regard a situation where a model method does not have 
> sufficient information as exceptional; the controller which invoked 
> the method can present an alert sheet in response to caught 
> exceptions.


This is probably my biggest struggle in cocoa programming. 
Controllery things keep sneaking into my models. I will keep your 
message around to beat against my head until I internalize it. Thank 
you.