From: MikkelFJ <mikkelj-anti-spam@...1.dknet.dk>
Date: 2001-11-29T07:13:31+09:00
Subject: [ruby-talk:26844] Re: Ref Counting (was KDE or GNOME curiosity question...)


"Paul Brannan" <pbrannan@atdesk.com> wrote in message
news:Pine.LNX.4.40.0111281609220.2741-100000@zaphod.atdesk.com...
> On Thu, 29 Nov 2001, mark hahn wrote:
>
> > I'm thinking now that using scope is the only good way to get quick
> > finalization, with the fopen/block trick being the best example.
>
> The problem with scoping is that it doesn't work if you need to share the
> object among many different other objects.
>
> I've never personally run into this problem, but I know that it can come
> up.  Just recently, in [ruby-talk:25477], there was talk of wanting to
> close a database connection automatically.  To summarize, the author
> wanted to use a finalizer, but he was (fortunately) able to use scoping
> instead.  Matz said he was in favor of explicit disconnection from the
> database.  However, imo, explicit disconnection could be error-prone, but
> it's probably the only reliable way to do this in Ruby for the cases where
> a block will not suffice.

But you can combine scoping with subscribe unsubscribe as mentioned in other
mail

class ResourceHandle
  def  initialize(resource)
    @count = 0
    @resource = resource
  end
  def subscribe()
    @count = @count + 1
  end
  def unsubscribe()
    @count = @count - 1
    if @count = 0
      @resource.close
    end
  end
end

Usercode with block scope magic left as an exercise.



MikkelFJ