Groups > comp.lang.python > #22024

Re: Best way to disconnect from ldap?

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Date	Thu, 22 Mar 2012 09:00:50 -0500
From	Tycho Andersen <tycho@tycho.ws>
To	Chris Rebert <clp2@rebertia.com>
Subject	Re: Best way to disconnect from ldap?
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On Thu, Mar 22, 2012 at 06:27:45AM -0700, Chris Rebert wrote:
> On Thu, Mar 22, 2012 at 6:14 AM, Tycho Andersen <tycho@tycho.ws> wrote:
> > On Wed, Mar 21, 2012 at 04:49:54PM -0500, Tim Chase wrote:
> >> On 03/21/12 15:54, Chris Kaynor wrote:
> >> >As Chris Rebert pointed out, there is no guarantee as to when the
> >> >__del__ method is called. CPython will generally call it immediately,
> >> >however if there are reference cycles it may never call it
> >>
> >> And more maddeningly, modules/objects used/called from within the
> >> __del__ may have already gone out of scope, producing
> >> head-scratching errors.  I've been bitten by this enough times that
> >> I just stopped using __del__ completely.
> >
> > I've had similar experiences. In fact, in light of all this - why does
> > __del__ exist at all? Novice python users may (reasonably) assume it
> > behaves similarly to a C++ destructor (even though the docs warn
> > otherwise).
> >
> > Given that you can't trust __del__, is there a legitimate use case for
> > it?
> 
> Writing resource classes (like `file`) in C? Their __del__()s
> typically involve little/less Python-level stuff and thus less
> paranoia need be exercised.

Sure, but you still have no guarantee that __del__ will ever be
called, so it's a bad idea to rely on it to clean up anything.

> There is somewhat of a perverse incentive in having such last-ditch
> clean-up mechanisms though. "This code seems to work fine without
> `with`, so why bother changing it?"

Yeah, I guess I can see doing something like:
  __del__ = __exit__
but anything beyond that seems risky...

\t

Thread

Best way to disconnect from ldap? John Gordon <gordon@panix.com> - 2012-03-21 19:30 +0000
  Re: Best way to disconnect from ldap? "J. Cliff Dyer" <jcd@sdf.lonestar.org> - 2012-03-21 16:21 -0400
  Re: Best way to disconnect from ldap? Chris Rebert <clp2@rebertia.com> - 2012-03-21 13:34 -0700
  Re: Best way to disconnect from ldap? Chris Kaynor <ckaynor@zindagigames.com> - 2012-03-21 13:54 -0700
  Re: Best way to disconnect from ldap? Tycho Andersen <tycho@tycho.ws> - 2012-03-22 08:14 -0500
    Re: Best way to disconnect from ldap? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-03-22 17:26 +0000
      Re: Best way to disconnect from ldap? Tim Chase <python.list@tim.thechases.com> - 2012-03-22 12:54 -0500
      Re: Best way to disconnect from ldap? Terry Reedy <tjreedy@udel.edu> - 2012-03-22 15:27 -0400
      Re: Best way to disconnect from ldap? Tycho Andersen <tycho@tycho.ws> - 2012-03-22 16:02 -0500
  Re: Best way to disconnect from ldap? Chris Rebert <clp2@rebertia.com> - 2012-03-22 06:27 -0700
  Re: Best way to disconnect from ldap? Tycho Andersen <tycho@tycho.ws> - 2012-03-22 09:00 -0500
  Re: Best way to disconnect from ldap? John Gordon <gordon@panix.com> - 2012-04-05 18:38 +0000
    Re: Best way to disconnect from ldap? Michael Ströder <michael@stroeder.com> - 2012-04-05 20:56 +0200

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