[MacRuby-devel] Need to Write Core Data Accessors in MacRuby?

[Eloy Duran]

I have no experience with Core Data, but if you are looking to make
repetitive work easy then don't forget about the metaprogramming
possibilities with Ruby. Taking your example, you could create class
method like the following:

class Model
  def self.core_data_accessor(name)
    class_eval(%{
      def add#{name}Object(value)
        changedObjects = NSSet.setWithObject(value)
        willChangeValueForKey('#{name}',
withSetMutation:NSKeyValueUnionSetMutation,
usingObjects:changedObjects)
        primitiveValueForKey('#{name}').addObject(value)
        didChangeValueForKey('#{name}',
withSetMutation:NSKeyValueUnionSetMutation,
usingObjects:changedObjects)
      end
    })
  end

  core_data_accessor 'SubFolders'
  core_data_accessor 'OtherFolders'
  # etc
end

HTH

On Tue, Jun 28, 2011 at 5:55 PM, Shannon Love <techzen at me.com> wrote:
> I'm not to the point of wiring up the UI yet. I will employ bindings when I
> do so but at the moment I am creating a complex data model using
> NSManagedObject subclasses with lots of customized behaviors. I do this all
> the time in Objective-c but I am uncertain how to go about doing so in
> MacRuby.
>  The @dynamic processor in Objective-C 2.0 autogenerates attribute and
> relationship accessors except for the to-many relationship convenience
> methods but obviously MacRuby has no such capability. I don't think the
> `attr_accessor ` in ruby will generate the proper core data accessors.
> I suppose my real question is: Do we have to write all the accessors like we
> used to do in the early days of Core Data in Objective-s 1.0 or is there
> some functionality in ruby or MacRuby that obviates the need to do so?
> Thanks,
> Shannon
>
>
> On Jun 27, 2011, at 5:55 PM, Matt Aimonetti wrote:
>
> Hey Shannon,
> I'm not sure I fully understand, but you should be able to just set the
> accessor and do the binding via Xcode as shown
> here: http://ofps.oreilly.com/titles/9781449380373/_core_data.html
> Let me know if that doesn't answer your question.
> - Matt
>
> On Mon, Jun 27, 2011 at 3:45 PM, Shannon Love <techzen at me.com> wrote:
>>
>> Howdy,
>>
>> I've Core Data a lot in Objective-c and now I am trying to use it in
>> MacRuby. It occurs to me that I might need to create the to-many
>> relationship accessors just like you have to do in Objective-C.
>>
>> To clarify: Suppose I have a data model that models a file structure and
>> which looks like this:
>>
>> Folder{
>>   name:string
>>   parent<<-->Folder.subFolders
>>   subFolders<-->>Folder.parent
>>   files<-->>File.folder
>> }
>> File{
>>   name:string
>>   folder<<-->Folder.file
>> }
>>
>> In Objective-C, I would normally have methods in the `Folder` class that
>> would look like:
>>
>> addSubFoldersObject:
>> removeSubFoldersObject:
>> addSubFoldersObjects:
>> removeSubFoldersObjects:
>>
>> The methods themselves would use look something like:
>>
>> - (void)addSubFoldersObject:(FetchedPropertyExtractor *)value {
>>     NSSet *changedObjects = [[NSSet alloc] initWithObjects:&value
>> count:1];
>>     [self willChangeValueForKey:@"SubFolders"
>> withSetMutation:NSKeyValueUnionSetMutation usingObjects:changedObjects];
>>     [[self primitiveValueForKey:@"SubFolders"] addObject:value];
>>     [self didChangeValueForKey:@"SubFolders"
>> withSetMutation:NSKeyValueUnionSetMutation usingObjects:changedObjects];
>>     [changedObjects release];
>> }
>>
>> Do you have to do the same thing in MacRuby or will the normal ruby set
>> operations suffice?
>> Thanks,
>> Shannon Love a.k.a TechZen
>>
>>
>>
>> _______________________________________________
>> MacRuby-devel mailing list
>> MacRuby-devel at lists.macosforge.org
>> http://lists.macosforge.org/mailman/listinfo.cgi/macruby-devel
>>
>
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