Re: Question about Saving a document
Re: Question about Saving a document
- Subject: Re: Question about Saving a document
- From: Paul Lynch <email@hidden>
- Date: Wed, 14 Jun 2006 21:45:53 +0100
On 14 Jun 2006, at 11:48, Francis Derive wrote:
On Jun 5, 2006, at 12:50 PM, Paul Lynch wrote:
On 5 Jun 2006, at 11:42, Francis Derive wrote:
My document nib has :
- an instance of a simple model object,
You don't want to have your model instantiated in the nib, in
general, although there are situations where it could be appropriate.
Paul,
You say "You don't want to have your model instantiated in the
nib" but, in the Apple's "Developing Cocoa Applications Using
Bindings: A Tutorial", this is what is made : an instance of the
model named "Converter" is instanciated in the nib, then an
instance of an NSObjectController - the content of which is the
above model, etc...
You shouldn't assume that Apple examples all follow best practices
(they try, but can't always succeed), nor that their examples are
always entirely typical usages.
What could I do from a nib if there were nothing in it ?
This question indicates that you haven't understood the example very
well. A nib will certainly contain many view objects (windows,
buttons, fields, etc), as well as instantiated controllers, both
bindings controllers and your own classes.
Your controller objects will interact with both view objects, and
model objects. Most commonly, model objects are instantiated inside
your controllers. In a few cases, and the CurrencyConverter is one,
you can have a model object that is instantiated inside the nib,
simply because it is convenient to do so. It isn't a very typical
model object.
I would like a comment from you.
Now I keep these scheme from the tutorial, and I will ask how to
extend the Cocoa bindings Tutorial so as to save such documents -
through bindings : I tried but doesn't succeed and understand nothing.
You need to implement a connection from your document controller to
the converter object, and refer to it in the load and save methods.
See previous posts. However, there isn't any reasonable way to
implement load functionality unless you move the converter object
inside your controller, as you can't just replace the nib
instantiated object. Again, see previous posts.
You aren't going to be able to simply "extend" this example;
sometimes, you have to make changes to previous approaches into order
to move forwards. Perhaps some of the Apple documentation people on
this list will take your suggestion and update the tutorial for you.
Paul
A bientôt.
Francis
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