From: Paul Brannan <pbrannan@...>
Date: 2002-05-29T01:56:22+09:00
Subject: Re: Stymied by Ruby's garbage collector

On Tue, May 28, 2002 at 10:34:19PM +0900, Nat Pryce wrote:
> I've never missed the lack of destructors in languages other than C++.
> Perhaps its because in C++, it is idiomatic to use the destructor as part of
> the object's protocol, while in OO languages with GC, as you say, one
> implements those parts of the protocol as explicit method calls.  I usually
> only use finalisers to ensure safety in the presence of unexpected
> exceptions, rather than to clean up objects when no longer needed, as C++

C++ destructors are also used to clean up when an exception is thrown.
I tend to use ensure blocks to do this in Ruby, because with finalizers,
you have to make sure you aren't somehow accidentally holding a
reference to the object (via a proc or continuation or something).

> destructors are.  In my experience it's much easier to write exception-safe
> code in Ruby than it is in C++. Swings and roundabouts...

If your objects hold only pointers and POD types, then writing
exception-safe code in C++ becomes much easier (try writing an
assignment operator for an object that doesn't holds non-POD data and
you will see what I mean).  In Ruby, objects can't hold anything other
than object references (pointers), so the problem becomes much simpler.
It's not a matter of idioms, but of features.

Paul