From: Massimiliano Mirra <list@...>
Date: 2002-08-05T05:51:40+09:00
Subject: Re: Detecting when an instance variable is created/set

On Mon, Aug 05, 2002 at 04:59:40AM +0900, Harry Ohlsen wrote:
> > Would it be enough for you to catch creation of instance variables in
> > each method before it returns, to do what you want with them
> > (e.g. swapping their value with a wrapper of the value)?
> 
> Unfortunately, for it to be useful to me, I'd specifically need it to work in 
> initialize() as well.

I don't know why it does not work in initialize (I assumed it would).
A dirty fix:

module Initializer
  def initialize(*args)
    puts "Here I'll handle these variables: #{instance_variables.inspect}"
  end
end

module MonitorVariables
  ...
end

class Test
  def initialize(*args)
    @a = 1
    @b = 'world'
    super(*args)
  end

  ...

  include MonitorVariables, Initializer
end


t = Test.new

-> Here I'll handle these variables: ["@a", "@b"]

I also don't know why, if put in MonitorVariables, initialize won't be
called, and needs to be put in a different module.

> > If so, try the following.  Beware, hacking into that class_eval is
> > quoting hell, as there are two levels of weak quotes.
> 
> <very deep block of code snipped>
> 
> Wow!  By the time I feel comfortable that I completely understand that block 
> of code, I'll be able to put "Ruby guru" on my resume!  You obviously already 
> have it on yours :-).

Nah, just a tad more than a rookie, really.


Massimiliano