Re: Large over 100K pixel high ruler scroll view
Re: Large over 100K pixel high ruler scroll view
- Subject: Re: Large over 100K pixel high ruler scroll view
- From: Jens Alfke <email@hidden>
- Date: Wed, 31 Aug 2011 00:02:26 -0700
On Aug 30, 2011, at 9:49 PM, Julie Porter wrote:
> What I do not get, is why an accessor such as an abstract getObject can not get the Object from the open and instantiated MyDocument class.
I think maybe you’re not thinking the right way about “instantiated” (and “open” really doesn’t mean anything here.) “Instantiating” means “creating an instance”, i.e. creating an object that belongs to that class. It’s comparable to malloc. Saying “MyDocument is instantiated” just means that, somewhere in memory, there is an object whose class is MyDocument. It does not imply that there is any way to find that object given only knowledge of the class. There could be millions of MyDocument objects at any moment
The getObject accessor is a method of MyDocument, but methods have to be called on objects. Otherwise it’s like calling Carbon’s GetWindowTitle without giving it a WindowPtr. The state that you want to access belongs to an individual MyDocument object, so there is no way to get it without having a reference to that object.
> What does IB have to do with my database and communication between functions? I thought this was for things like buttons and cells so that when one presses a button the value in a cell is passed to the function.
Wiring in IB defines connections between arbitrary objects. It just happens that most of the objects you wire up are views. When you define a connection in a nib, then when the objects are loaded into memory they will be set up to point to each other.
> I think cocoa is the other way around, Where the document which has the array of dictionaries I want is not visible to the View because the view is not open to the document.
Honestly, the metaphor doesn’t apply at all. There is no such thing as “open” or “visible”. There is no state involved. Trying to make analogies to PostScript is just going to confuse you even more. The document and view are fancy structs in memory, and for one to be able to access the contents of another, it has to have a pointer to it as one of its members. Does that make more sense?
—Jens_______________________________________________
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