Re: [Rubycocoa-talk] RubyCocoa, CoreData, & NSPersistentDocumentTutorial

[kimura w. <ki...@us...>]

Hi,

I'm trying this tutorial.


Thu, 3 Nov 2005 23:13:03 +0000, Jonathan Paisley wrote:
>On 3 Nov 2005, at 21:31, Rupert Barrow wrote:
>

>Since you're using Core Data, all the data members of the class are  
>already managed for you. Therefore, you should not define firstName  
>and lastName as accessors, nor should you use ruby @firstName/ 
>@lastName variables.
>
>Instead, just access firstName etc as if it were already defined as  
>an accessor (or perhaps you need to use setValue:forKey: and  
>valueForKey:). RubyCocoa will forward the call through to Objective  
>C, where Core Data will handle the request for you.
>

It's right. To access attributes of an Employee, we have to use 
setValue:forKey and valueForKey:. 

for example:
------------
  def fullNameAndID
    return OSX::NSString.stringWithString(valueForKey("lastName").to_s + 
           ", " +  valueForKey("firstName").to_s)
  end
------------


I felt that was not smart. I defined a method "kvc_wrapper". This method 
defines accessors wrapping "valueForKey:" and "setValue:forKey:".
# tell me a better name of "kvc_wrapper", please.

my Employee.rb:
---------------
require 'osx/cocoa'
require 'osx/coredata'

# add kvc_wrapper
module OSX

  module NSKVCBehaviorAttachment

    # accessor for keys defined in Cocoa
    def kvc_wrapper(*keys)
      keys.each do |key|
        class_eval <<-EOE_KVC_WRAPPER,__FILE__,__LINE__+1
        def #{key}
          valueForKey("#{key}")
        end
        def #{key}=(val)
          setValue_forKey(val, "#{key}")
        end
        EOE_KVC_WRAPPER
      end
    end
  
  end

end

# Employee class 
class Employee < OSX::NSManagedObject
  
  kvc_depends_on [:lastName, :firstName], :fullNameAndID

  # define wrappers
  kvc_wrapper :lastName, :firstName, :employeeID 

  def fullNameAndID
    sprintf('%s, %s (%d)', lastName.to_s, firstName.to_s, employeeID)
  end
  
end
---------------


I think that is possible to define wrappers automatically from 
NSManagedObjectModel#entities -> NSEntityDescription, but I do not
know how to implement.



-- 
kimura wataru