module AwsSingularResourceMixin

directly-including class - we can't see second-order includers.
We'd like to put it in AwsResourceMixin, but included only sees the
TODO: DRY up. This code exists in both the Singular and Plural mixins.
unit testing.
having to know which is selected. This is mainly used for
provides a mechanism to create and use backends without
This sets up a class, AwsSomeResource::BackendFactory, that

def self.included(base)
  # Create a new class, whose body is simply to extend the
  # backend factory mixin
  resource_backend_factory_class = Class.new(Object) do
    extend AwsBackendFactoryMixin
  end
  # Name that class
  base.const_set('BackendFactory', resource_backend_factory_class)
end

def exists?
  @exists
end