From: Mark Hubbart <discordantus@...>
Date: 2004-11-16T03:28:39+09:00
Subject: Re: Finalizers...

Hi,

On Wed, 10 Nov 2004 21:23:04 +0900, Michael Neumann <mneumann@ntecs.de> wrote:
> Hi,
> 
> Are finalizers (ObjectSpace.define_finalizer) executed atomicly? Or can
> they be interrupt by other finalizers (or threads)?
> 
> I've noticed that finalizers can't raise exceptions. They silently
> abort. That's a feature, but hard to find bugs in finalizers ;-)

% ruby <<EOP
f = lambda do
  begin
    0/0
  rescue ZeroDivisionError => e
    puts e, e.backtrace
  end
end
ObjectSpace.define_finalizer "foo", f
EOP
divided by 0
-:3:in `/'
-:3
-:1:in `call'
-:8

One could imagine an ObjectSpace.define_debug_finalizer:

### untested ###
def ObjectSpace.define_debug_finalizer(obj, callable, io = STDERR)
  wrapper = lambda do |id|
    begin
      callable.call(id)
    rescue Exception=>e
      io.puts e, e.backtrace
    end
  end
  ObjectSpace.define_finalizer obj, wrapper
end

cheers,
Mark