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Here's a better version of my solution.  Obviously these modules would 
have to be included in Object to work.  The names should be self 
explainitory.  All lines are less than 80 chars. 

module Attribute20PercentGolfed
  def attribute(arg, &b)
    return attribute(arg.keys[0]) { arg.values[0] } if arg.class == Hash
    define_method(arg) do
      init = block_given? && !instance_eval("defined? "+"@"+arg)
      init ? send(arg+"=",instance_eval(&b)) : 
instance_variable_get("@"+arg)
    end
    define_method(arg+"?") { !!send(arg) }
    attr_writer(arg)
  end
end

module Attribute75PercentGolfed; def attribute(a, &b)
  return attribute(a.keys[0]) { a.values[0] } if a.class == Hash
  define_method(a) { block_given? && !instance_eval("defined? "+"@"+a) ?
    send(a+"=",instance_eval(&b)):instance_variable_get("@"+a) }
  define_method(a+"?") { !!send(a) } && attr_writer(a); end; end


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 filename="knowledge.rb"

module Attribute20PercentGolfed
  def attribute(arg, &b)
    return attribute(arg.keys[0]) { arg.values[0] } if arg.class == Hash
    define_method(arg) do
      init = block_given? && !instance_eval("defined? "+"@"+arg)
      init ? send(arg+"=",instance_eval(&b)) : instance_variable_get("@"+arg)
    end
    define_method(arg+"?") { !!send(arg) }
    attr_writer(arg)
  end
end

module Attribute75PercentGolfed; def attribute(a, &b)
  return attribute(a.keys[0]) { a.values[0] } if a.class == Hash
  define_method(a) { block_given? && !instance_eval("defined? "+"@"+a) ?
    send(a+"=",instance_eval(&b)):instance_variable_get("@"+a) }
  define_method(a+"?") { !!send(a) } && attr_writer(a); end; end

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