Comment 3 for bug 1223524

Reviewed: https://review.openstack.org/46363
Committed: http://github.com/openstack/keystone/commit/5e04343ff5b5f6f7ac896492ebdb4f992d07be47
Submitter: Jenkins
Branch: master

commit 5e04343ff5b5f6f7ac896492ebdb4f992d07be47
Author: Brant Knudson <email address hidden>
Date: Thu Sep 12 16:07:13 2013 -0500

    Optional dependency injection

    This adds support for optional dependencies using Keystone
    dependency injection.

    A new decorator for classes is provided.

     @dependency.optional('optional_api_1', 'optional_api_2')

    If there's a provider for the dependency, the attribute
    will be set to the provider instance, otherwise the attribute
    will be set to None.

    This can be used in combination with required dependencies.

    Related-bug: #1223524
    Change-Id: I2b987f10a7bc85efab136ae9e84606e666494246