From: Brett Williams <brett_williams@...>
Date: 2002-09-11T04:35:27+09:00
Subject: use of finalizers

After months of little activity here, I have a second question for today :)

I am trying to use a finalizer for a little cleanup work with some C++ 
extensions, but I am missing something:
class Foo
  def initialize()
  puts "Constructed new object... #{self.id}"
    ObjectSpace.define_finalizer(self, Proc.new { |id|
                                   puts "Destroying #{id}"
    })
  end
end

if __FILE__ == $0
  foo = Foo.new
  foo = nil
  GC.start
  foo = Foo.new
  ObjectSpace.define_finalizer(foo, Proc.new { |id| puts "Outside #{id}"})
  foo = nil
  GC.start
end

output:

vor-lord:scripts/ruby> ruby Foo.rb 
Constructed new object... 537849088
Constructed new object... 537849068
Outside 537849068


So the finalizer isn't called when it is registered in the constructor (in 
fact I've tried several ways to define a finalizer for self without 
success).

What is the principle that I am breaking?

-- 
The key of strategy... is not to choose a path that leads to victory, but 
to choose so that all paths lead to a victory.
-- L.M. Bujold