Re: [Rubycocoa-talk] Problem with YAML::load in AppController

[Allison N. <dem...@ma...>]

Stephyn,

You have to be very careful using YAML with NSObjects - YAML doesn't  
know how to save the NSObject part of the object, or at least, it  
doesn't know how to reinitialise the object correctly when you do a  
YAML.load.

When I ran into a similar problem (I was trying to use YAML data with  
an NSOutlineView), I eventually solved it by implementing the NSCoding  
protocol.  The code looks like this:

   def encodeWithCoder(coder)
     coder.encodeObject_forKey(@exercise_machines, "exercise_machines")
     coder.encodeObject_forKey(@programs, "programs")
     coder.encodeObject_forKey(@schedules, "schedules")
   end

   def initWithCoder(coder)
    init
    @exercise_machines = coder.decodeObjectForKey("exercise_machines")
    @programs = coder.decodeObjectForKey("programs")
    @schedules = coder.decodeObjectForKey("schedules")
    self
   end

   def save
     NSLog("Saving archive")
     result = NSKeyedArchiver.archiveRootObject_toFile_(self, FILE_NAME)
   end

   def load
     lib = NSKeyedUnarchiver.unarchiveObjectWithFile(FILE_NAME)
   end

Otherwise you get all sorts of bad things happening - objects that  
blow up when loading, objects that die when the NSTable tries to call  
NSObject methods on your YAML-loaded objects etc etc. Bad things.

Hope that helps.

Alli

Le 26 juil. 08 à 08:06, Stephyn Butcher a écrit :

> Hi all,
>
> I have a very simple app I'm trying to write to spike out some key  
> portions of an app I'm planning to write.
>
> The application is not document based but I do want to be able to  
> save and load the object model. The "preferred" form is YAML with  
> import/export using XML. The application is dirt simple. Just an  
> array of Friends visible through a NSTable and the Friend objects  
> themselves which can be edited.
>
> I can successfully save the @friends array as a YAML file  
> (saveFriends)...but I get thrown into the debugger every time I  
> tried to load a YAML file (openFriends). I've narrowed it down to  
> YAML::load as the line that crashes (I can read the file, and print  
> out the contents to NSLog just fine).
>
> Any ideas?
>
> If you're curious and want to kick the tires, you can download the  
> project at http://homepage.mac.com/stephyn/Friends.zip
>
> Thanks a bunch.
>
> Cheers,
> Steve
>
>
> ---Friend.rb
> require 'osx/cocoa'
>
> class Friend < OSX::NSObject
> 	include OSX
> 	
> 	kvc_accessor :name, :email, :cell
> 	
> 	def init
> 		if super_init
> 			@name = "New Friend"
> 			@email = "New Email"
> 			@cell = "New Cell"
> 			self
> 		end
> 	end
> end
>
> ---AppController.rb
> require 'osx/cocoa'
> require 'yaml'
>
> class AppController < OSX::NSObject
> 	include OSX
> 	
> 	kvc_accessor :friends
> 	
> 	def init
> 		if super_init
> 			@friends = NSMutableArray.array
> 			self
> 		end
> 	end
> 	
> 	def saveFriends( sender)
> 		friends = @friends.to_ruby
> 		
> 		panel = NSSavePanel.savePanel
> 		if panel.runModal == NSFileHandlingPanelOKButton
> 			filename = panel.filename.to_ruby
> 		else
> 			return
> 		end
> 		File.open( filename, "w") { |file| file.puts friends.to_yaml}
> 	end
> 	ib_action :saveFriends
> 	
> 	def openFriends( sender)
> 		panel = NSOpenPanel.openPanel
> 		if panel.runModal == NSFileHandlingPanelOKButton
> 			filename = panel.filename.to_ruby
> 		else
> 			return
> 		end
> 		@friends = YAML::load( File.open( filename, "r"))
> 	end
> 	ib_action :openFriends
> end
>
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