From: hvs1@... (Harry)
Date: 2004-07-07T04:42:39+09:00
Subject: [RubyCocoa] Cocoa Bindings? (cont.)

Hello,

(to Kevin Bullock in this group: when searching for a solution, I saw
your answer to my earlier question in c.l.r. about this, not here in
c.l.r., but on some ruby-talk site, where you asked for the source
code of the dummy app: I included it here. I also followed the
instructions suggested on the ruby-cocoa mailing list at sourceforge,
alas, no show yet ...)

My first question is: has anyone had any succes in building and
running a RubyCocoa / Cocoa Bindings (aka Cocoa Controller Layer)
project? I tried to do a dummy-app along the execellent tutorial at
(using ruby1.8 instead of ObjC):

http://www.macdevcenter.com/pub/a/mac/2004/04/06/cocoa.html?page=1

Building the interface according this tutorial and test-driving it in
Interface Builder works fine.


In a first attempt, my Book.rb looked like this:

class Book < OSX::NSObject
    attr_accessor :title
    attr_accessor :author
end

Running the app gave me this error:

/Users/hvs/tmp/bibliotecha/build/bibliotecha.app/Contents/Resources/ 
 rb_main.rb:19:in
 `NSApplicationMain': NSApplicationMain - NSUnknownKeyException -
 [<Book 0x4f2540> valueForUndefinedKey:]: this class is not key value
 coding-compliant for the key title. (OSX::OCException)
 	from  
 /Users/hvs/tmp/bibliotecha/build/bibliotecha.app/Contents/Resources/ 
 rb_main.rb:19

After reading some more docs on Apple's ADC site, about key value
coding (KVC) -compliancy, I change my code to:

class Book < OSX::NSObject
    attr :title
    attr :author
    
    def title
        return @title
    end
    
    def author
        return @author
    end
    
    def setTitle(title)
        @title = title
    end
    
    def setAuthor(author)
        @author = author
    end
end

It's ugly, but a KVC-compliant object needs set<Key> methods. But this
gave me the same error.

How to make Book KVC-compliant???

thx,
Harry