From: Matthew B Gardner <weather@...>
Date: 2007-08-19T09:58:55+09:00
Subject: Re: Problem with Array#delete

Hello -

On Saturday 18 August 2007 20:32, David A. Black wrote:
> Hi --
>
> On Sun, 19 Aug 2007, Matthew B Gardner wrote:
> > Hello -
> >
> >> On Saturday 18 August 2007 17:56, David A. Black wrote:
> >> Hi --
> >>
> >> On Sun, 19 Aug 2007, Matthew B Gardner wrote:
> >>> Thank you to everyone who has tried to help me with this today -- I
> >>> know for certain -what- the problem is now, after adding in some
> >>> testing. My Character class, for whatever reason, is using == to
> >>> evaluate class. So, when I am trying to use Array#delete
> >>> (array.delete(self) for a Character object), it's deleting every
> >>> Character object in that array instead of just that single instance.
> >>> I've tried to fix this issue by defining the == method in my Character
> >>> class like this:
> >>>
> >>> def Character
> >>> 	def == obj
> >>> 		self.equal?(obj)
> >>> 	end
> >>> end
> >>>
> >>> However, this doesn't initially work -- I have to reload the file
> >>> during runtime for it to utilize the above method. For sake of clarity,
> >>> this is what I mean:
> >>>
> >>> Start program...
> >>> a = Character.new
> >>> b = Character.new
> >>> a == b #=> true
> >>> Reload character.rb file while program is running...
> >>> a == b #=> false
> >>>
> >>> Hopefully that gets my meaning across. I'm not sure why Character#==
> >>> isn't initially getting used, or if there's something wrong with my
> >>> declaration. I'm also not sure why Character#== (prior to my defining
> >>> Character#==) is comparing class and my other classes aren't.
> >>>
> >>> I hope that this description is satisfactory -- and thank you for any
> >>> help that can be offered.
> >>
> >> I still can't tell what's happening without seeing actual code that's
> >> doing what you're describing. Have you got a running example?
> >>
> >>
> >> David
> >
> > Here's the pertinent code:
> >
> > require 'singleton'
> >
> > class Engine
> >  include Singleton
> >  attr_reader :world
> >  def initialize
> >    @world = nil
> >  end
> >
> >  def startup
> >    @world = World.new
> >  end
> > end
> >
> > class World
> >  attr_accessor :characters
> >  def initialize
> >    @characters = []
> >  end
> > end
> >
> > class Root
> >  def initialize name
> >    @name = name
> >  end
> > end
> >
> > class Account
> >  attr_accessor :character
> >  def initialize
> >    @character = nil
> >  end
> >  def foo
> >    @character = Character.new "testname", self
> >    world.characters << @character
> >  end
> > end
> >
> > class Mind < Root
> >  def initialize name
> >    super(name)
> >  end
> > end
> >
> > class Character < Mind
> >  def initialize name, acc
> >    super(name)
> >    @account = acc
> >  end
> >  def quit
> >    world.characters.delete self
> >  end
> > end
> >
> > def world
> >  Engine.instance.world
> > end
> >
> > Engine.instance.startup
> > acc1 = Account.new
> > acc1.foo
> > acc2 = Account.new
> > acc2.foo
> > p world.characters.size
> > acc1.character.quit
> > p world.characters.size
> >
> >
> > However, this isn't reproducing my error (as you can see from the
> > printout). As I've said before, I have other World#array variables that
> > function the exact same way and don't run into the error I've been
> > experiencing. Hopefully the code helps pinpoint (or at least hint at) why
> > Character#== is evaluating class instead of identity, or why I have to
> > reload the file for my defined Character#== to take effect.
>
> I'm feeling a little stupid, but where do you define Character#== ?
>
>
> David

I didn't include it with my code, but I wrote it in like this:

class Character < Mind
	def initialize name, acc
		super(name)
		@account = acc
	end
	def == obj
		self.equal?(obj)
	end
	def quit
		world.characters.delete self
	end
end

This addition only works after I reload the character.rb file while the 
program is running. Initially (until I reload the file), 
world#characters.delete deletes all of the Character objects -- after the 
reload it only delete the instance.

Does this help at all?

Thanks again,
Matt