From: Robert Klemme <shortcutter@...>
Date: 2007-02-21T00:50:06+09:00
Subject: Re: Deconstructor to close file

On 20.02.2007 14:12, Austin Ziegler wrote:
> On 2/20/07, Robert Klemme <shortcutter@googlemail.com> wrote:
>> On 20.02.2007 01:00, Austin Ziegler wrote:
>> > There is no meaningful concept of a destructor in Ruby. There are
>> > finalizers, but they're not guaranteed to be called.
>> Are you sure about that?  I know the statement to be true for Java but
>> in which situation (other than an interpreter crash) is a finalizer not
>> invoked?
> 
> I recall reading a few things over the last couple of years. On
> program termination, I think they will be called,

Yes.  Actually I found a regular way to prevent invocation:

robert@fussel ~
$ ruby -e 'o=Object.new;ObjectSpace.define_finalizer(o) {p 222};exit 1'
222

robert@fussel ~
$ ruby -e 'o=Object.new;ObjectSpace.define_finalizer(o) {p 222};exit! 1'

robert@fussel ~
$

So there is at least /one/ other way besides a process crash.  I didn't 
think of exit! before.  Good that we double checked. :-)

 > but things could
> happen to keep an object around a lot longer than you think -- which
> means that it's not something to trust.

Yeah, don't trust the timing.  And I definitively agree that there are 
often better means than finalizers.

Kind regards

	robert