From: "Víctor Adrián de la Cruz Serrano" <adrian@...>
Date: 2009-11-11T16:58:21+09:00
Subject: Need help to detect error

I don't know what am I doing wrong, can anyone help me?
These two programs look very similar, but they yield different results.
Can anyone confirm this "error"?


=================================================================
# FAILING EXAMPLE
=================================================================
class Battlefield
  attr_accessor :teams
  def initialize
    @teams = []
  end
  def add_team(team)
    @teams << team
    team.bparent = self
  end
end

class Team
  attr_accessor :members, :bparent
  def initialize
    @members = []
    @bparent = nil
  end
  def add_member(child)
    @members << child
    child.team = self
  end
end

class Warrior
  attr_accessor :team
  def initialize
    @team = nil
  end
end

w = Warrior.new
t = Team.new
t.add_member(w)
b = Battlefield.new
b.add_team(t)
b.inspect
#Convert to YAML and back
y = YAML.load(b.to_yaml)
#Now have a look at the "members" array inside a team... it's gone
y.inspect
y.teams.first.members.inspect


=================================================================
# GOOD EXAMPLE
=================================================================
require 'yaml'

class Battlefield
  attr_accessor :teams
  def initialize
    @teams = []
  end
  def add_team(team)
    @teams << team
    team.parent = self
  end
end

class Team
  attr_accessor :members, :parent
  def initialize
    @members = []
    @parent = nil
  end
  def add_member(child)
    @members << child
    child.team = self
  end
end

class Warrior
  attr_accessor :team
  def initialize
    @team = nil
  end
end

w = Warrior.new
t = Team.new
t.add_member(w)
b = Battlefield.new
b.add_team(t)
b.inspect
#Convert to YAML and back
y = YAML.load(b.to_yaml)
#Now have a look at the "members" array inside a team, it's still there
y.inspect
y.teams.first.members.inspect