Repository base class.
Bases: object
Abstract base class for repositories.
The repository creates accessors on the fly, caches them, and returns a clone.
list of weak references to the object (if defined)
Returns an accessor for the given registered resource.
If this is the first request, an instance is created on the fly using the new() method and cached. The method always returns a clone of the cached accessor; this clone can later be used to look up the repository it was obtained from using the get_repository() class method.