[MacRuby-devel] NSArrayController

[Richard Kilmer]

On Sep 26, 2008, at 3:17 AM, Brad Wilson wrote:

>>
>> Here's an example of a key binding for an item that is an
>> NSCollectionViewItem (thus representedObject)
>>
>> image.bind "value", toObject:item,
>> withKeyPath:"representedObject.user.profile_image", options:nil
>>
>> So I am binding the value of the image to the item object's keypath:
>> representedObject.user.profile_image
>>
>> It looks like its complaining that the array of objects that you are
>> placing in ArrayController is causing
>> and exception that it is not KVC compliant?
>
> I guess that's the crux of my question - how do I make an object KVC
> compliant? Like I said, I tried attr_accessor employes, etc but didn't
> seem to have any luck.
>
> Thanks for the help. I'll try to get the code in a state to
> demonstrate my problem and send it up.
>
>
> Laurent - I'd be happy to send through any exercises. I'll send
> through a collection once I get some more done.
>
>
> Brad
> <snip>
>>

Brad,

Try this:

def initialize
  @employees = []
end

# for reading

def countOfEmployees
   @employees.length
end

def objectInEmployeesAtIndex(i)
   @employees[i]
end

# for writing

def insertObject(object, inEmployeesAtIndex:i)
   @employees[i,0] = object
end

def removeObjectFromEmployeesAtIndex(i)
   @employees.delete_at(i)
end

# you can also implement:

def replaceObjectInEmployeesAtIndex(i, withObject:object)
   @employees[i, 1] = object
end

There is an additional reader method but you are supposed to pass in a  
buffer and I don't think we can do that: getEmployees(buffer,  
range:range)

I found this in the Indexed Accessor Patters for To-Map Properties  
section of the KVC programming guide:

http://developer.apple.com/documentation/Cocoa/Conceptual/KeyValueCoding/Concepts/AccessorConventions.html#/ 
/apple_ref/doc/uid/20002174-BAJEAIEE

Hope that helps!

Laurent:

I wonder if we could generically add methods to ruby's Array to make  
it KVC compliant?

countOfObjects
objectInObjectsAtIndex(i)
insertObject(object, inObjectsAtIndex:i)
removeObjectFromObjectsAtIndex(i)

(and the two optional performance enhancing  
methods...replaceObjectInObjectsAtIndex(i withObject:object) and  
getObjects(objectsBuffer?, range:NSRange_instance))

Then we could have an Array generically be KVC compliant using the  
path: "objects"

Just a thought!

Best,

Rich