neutron/neutron/db/_resource_extend.py

62 lines
2.0 KiB
Python

# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
NOTE: This module shall not be used by external projects. It will be moved
to neutron-lib in due course, and then it can be used from there.
"""
from neutron.common import utils
# This dictionary will store methods for extending API resources.
# Extensions can add their own methods by invoking register_funcs().
_resource_extend_functions = {
# <resource1> : [<func1>, <func2>, ...],
# <resource2> : [<func1>, <func2>, ...],
# ...
}
def register_funcs(resource, funcs):
"""Add functions to extend a resource.
:param resource: A resource collection name.
:type resource: str
:param funcs: A list of functions.
:type funcs: list of callable
These functions take a resource dict and a resource object and
update the resource dict with extension data (possibly retrieved
from the resource db object).
def _extend_foo_with_bar(foo_res, foo_db):
foo_res['bar'] = foo_db.bar_info # example
return foo_res
"""
funcs = [utils.make_weak_ref(f) if callable(f) else f
for f in funcs]
_resource_extend_functions.setdefault(resource, []).extend(funcs)
def get_funcs(resource):
"""Retrieve a list of functions extending a resource.
:param resource: A resource collection name.
:type resource: str
:return: A list (possibly empty) of functions extending resource.
:rtype: list of callable
"""
return _resource_extend_functions.get(resource, [])