From: Edward Faulkner <ef@...>
Date: 2005-10-21T00:14:05+09:00
Subject: Re: Reflection, observ(er|able) instance vars?

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On Thu, Oct 20, 2005 at 09:01:45PM +0900, Hugh Sasse wrote:
> I'd like to hold a hash (number not Hash.new()) for this object so I
> can compare it quickly with another.  How do I detect that it has
> changed so that the hash gets updated correctly?

I think the simplest solution it to define your own attribute writer
and always use it:

class Test
  attr_reader :my_attribute
  def my_attribute=(val)
    @my_attribute = val
    @my_attribute_hash = make_hash(val)
  end

  def some_other_method
    # Do this
    my_attribute = something_new
    # Not this!
    @my_attribute = something_else
  end
end

regards,
Ed

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