From: Guillaume Cottenceau <gcottenc@...>
Date: 2005-04-13T19:58:58+09:00
Subject: Re: ability to run finalizers at a given point of a program?

> > Wait.. both calls to define_finalizer have a reference to foo as the
> > first argument, and both have a closure as second argument which
> > doesn't have a reference to foo.
> 
> Incorrect.  The first argument is irrelevant.
> ObjectSpace::define_finalizer is written this way probably to make
> things ugly.  You have to pass in the object you wish to attach a
> finalizer to, and that's what the first arg is for.

I wasn't pretending it would retain a reference, I was just comparing
both versions and underlined that both had that.
 
> In your version, foo is in-scope when the finalizer proc is created, so
> the proc captures foo *even though it is not explicitly used in the
> proc*.  That's right!  Just because you don't reference foo inside a
> closure doesn't mean it magically disappears for you.

Thanks, I was wrong on that very matter. I thought a closure only
captured the necessary environment, not the whole of it (what is
necessary being decided at closure creation time). And I can't
duplicate such ruby's behaviour in perl :/ Perl in my example doesn't
capture the whole environment when creating the closure:

http://www.zarb.org/~gc/t/prog/closures_wholecapture/

-- 
Guillaume Cottenceau - http://zarb.org/~gc/