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Re: Best way to disconnect from ldap?

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On Wed, Mar 21, 2012 at 12:30 PM, John Gordon <gordon@panix.com> wrote:
> I'm writing an application that interacts with ldap, and I'm looking
> for advice on how to handle the connection.  Specifically, how to
> close the ldap connection when the application is done.
>
> I wrote a class to wrap an LDAP connection, similar to this:
>
>    import ldap
>    import ConfigParser
>
>    class MyLDAPWrapper(object):
>
>        def __init__(self):
>
>            config = ConfigParser.SafeConfigParser()
>            config.read('sample.conf')
>
>            uri = config.get('LDAP', 'uri')
>            user = config.get('LDAP', 'user')
>            password = config.get('LDAP', 'password')
>
>            self.ldapClient = ldap.initialize(uri)
>            self.ldapClient.simple_bind_s(user, password)
>
> My question is this: what is the best way to ensure the ldap connection
> gets closed when it should?  I could write an explicit close() method,
> but that seems a bit messy; there would end up being lots of calls to
> close() scattered around in my code (primarily inside exception handlers.)
>
> Or I could write a __del__ method:
>
>        def __del__(self):
>            self.ldapClient.unbind_s()
>
> This seems like a much cleaner solution, as I don't ever have to worry
> about closing the connection; it gets done automatically.

Yes, but not necessarily in a timely manner. Since its uses reference
counting, CPython /just so happens/ to finalize
non-cyclically-referenced objects promptly when they go out of scope,
but Python-the-language makes no such guarantee, and indeed some of
the other Python implementations explicitly disclaim that there may be
a significant delay before finalization is performed.

> I haven't ever used __del__ before.  Are there any 'gotchas' I need to
> worry about?

In addition to the aforementioned problem regarding portability to
other Python implementations, see also the Warning box under:
http://docs.python.org/reference/datamodel.html#object.__del__

I concur with J.'s context manager suggestion.

Cheers,
Chris

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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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