From: Ned Konz <ned@...>
Date: 2002-05-26T09:04:43+09:00
Subject: Re: Stymied by Ruby's garbage collector

On Saturday 25 May 2002 01:22 pm, Yohanes Santoso wrote:

> I read the discussion page you referred to at
> http://www.rubygarden.org/ruby?DiscussionOnUsingFinalizers
>
> But I'm having difficulty in not keeping a reference to the gc'd
> object
>
> class SimpleLog
>  def initialize(where)
>    @logfile = File.new(where, "w+")
>    ObjectSpace.define_finalizer(@logfile, create_finalizer)
>    ObjectSpace.define_finalizer(self, create_finalizer)
>  end
>
>  def write(msg)
>    @logfile.puts msg
>  end
>
>  def create_finalizer
>    logfile = @logfile
>    proc {|id| puts "Finalizer on #{id}"
>               #now how do I close logfile without
>               #a reference to it?
>               logfile.puts "Closed properly"
>               logfile.close
>         }
>  end
> end

Part of the problem is that your create_finalizer is an instance 
method. Which means that self is the object itself. Which also means 
that the closure has a reference to self. It instead should probably 
be a class method.

As far as how to find the logfile, you can just pass it in to the 
create_finalizer:

ObjectSpace.define_finalizer(self, 
SimpleLog.create_finalizer(@logfile))

def SimpleLog.create_finalizer(logfile)
proc {|id| $stderr.puts("finalizer on #{id}")
logfile.puts "closed properly"
logfile.close }
end

-- 
Ned Konz
http://bike-nomad.com
GPG key ID: BEEA7EFE