From: narizona <narizona@...>
Date: 2006-05-24T05:14:02+09:00
Subject: Anobject question


In prag ruby the purchased copy, the following code fragment is shown. 
Look at where I added the >>>>.  That line VU.new(@volume.succ).  What I 
think it should do is create a new object instance of the class.  What 
it does though is it increments the attribute @volume on an existing 
object that uses the succ method.

I have verified that it does not create a new object by using 
myObject.object_id.  I am sure this is basic oop stuff but I do not 
think I have seen it.  Why does this happen like this?

I would have used an accessor to set the @volume.  I am surprised by the 
use of new here.

Thanks for your insight.

_Nathan

class VU
  include Comparable
  attr :volume
  def initialize(volume) # 0..9
    @volume = volume
  end
  def inspect
    '#' * @volume
  end
  # Support for ranges
  def <=>(other)
    self.volume <=> other.volume
  end
  def succ
    raise(IndexError, "Volume too big") if @volume >= 9
>>>>    VU.new(@volume.succ) <<<<<
  end
end

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