From: "Wolfgang Nádasi-donner" <ed.odanow@...>
Date: 2007-08-03T02:50:37+09:00
Subject: Re: finalizer not getting called

Joshua Chia wrote:
> I'm not familiar with all the nuances for blocks, but I only see that 
> the block makes no reference to self.  Why does it need to hold on to a 
> reference to self?

Blocks act as closures, which means, that variables not defined as block 
parameter but used inside the block, will be taken from the environment 
in which the block was defined. In this case the value of "self" - which 
refers the new defined object - must be saved for this purpose.

If you define the block outside of initialize, it will work.

>>>>> Code >>>>>
class A
  def initialize(b)
    puts "initializing #{self.object_id}"
    ObjectSpace.define_finalizer(self, b)
  end
end
a = A.new(proc{|id| puts "finalizing #{id}"})
puts "created #{a.object_id}"
a = nil
GC.start
ObjectSpace.each_object(A){|o|puts "still there: #{o.object_id}"}
puts 'exiting'
>>>>> Result >>>>>
initializing 24036640
created 24036640
finalizing 24036640
exiting
>>>>> EOE >>>>>
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