Metadata-Version: 2.0
Name: txdlo
Version: 0.1.1
Summary: A Twisted class for observing a set of deferreds.
Home-page: https://github.com/terrycojones/txdlo
Author: Terry Jones
Author-email: terry@jon.es
License: UNKNOWN
Download-URL: https://github.com/terrycojones/txdlo
Keywords: twisted deferred observer
Platform: UNKNOWN
Classifier: Programming Language :: Python
Classifier: Framework :: Twisted
Classifier: Development Status :: 4 - Beta
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: Apache Software License
Classifier: Operating System :: OS Independent
Classifier: Topic :: Software Development :: Libraries :: Python Modules
Provides: txdlo
Requires-Dist: Twisted

txdlo - a (Twisted) deferred list observer
==========================================

``txdlo`` is a Python package that provides a class called
``DeferredListObserver``.

As you might guess, ``DeferredListObserver`` lets you observe callback and
errback events from a list of `Twisted <http://twistedmatrix.com>`_
`deferreds <http://twistedmatrix.com/documents/current/core/howto/defer.html>`_.
You can add observers that will be passed information about deferreds
firing.  You can add deferreds to the observed list at any time, which is
very useful if you're dynamically creating deferreds that you want to
monitor.

The class can be used to easily build functions or classes that provide
deferreds that fire when arbitrary combinations of events from the observed
deferreds have occurred.

For example you can write functions or classes that support deferreds that

* Implement Twisted's ``DeferredList`` or simple variants of it, or that let
  you separate the various behaviors of ``DeferredList`` into simpler
  functions.
* Provide a deferred that fires when N of the observed deferreds have fired.
* Provide a deferred that ignores errors until one of the observed deferred
  succeeds, only firing with an error if all the observed deferreds fail.
* Or (a more involved example), suppose you have 3 methods that can return
  you a user's avatar: a fast local cache, a filesystem, and a slow network
  call to Gravatar. You want to write a deferred-returning function that
  launches all three lookups at once and fires its deferred with the first
  answer. But if the cache and/or filesystems fails first, you don't want
  to trigger an error, you instead want to take the result from Gravatar
  and add it to the cache and/or filesystem, as well firing the returned
  deferred with the result (wherever it comes from). Only if all three
  lookups fail do you want to errback the deferred you returned.

The source for ``txdlo`` lives at `https://github.com/terrycojones/txdlo
<https://github.com/terrycojones/txdlo>`_.


