stevedore/stevedore/named.py

97 lines
3.9 KiB
Python

from .extension import ExtensionManager
class NamedExtensionManager(ExtensionManager):
"""Loads only the named extensions.
This is useful for explicitly enabling extensions in a
configuration file, for example.
:param namespace: The namespace for the entry points.
:type namespace: str
:param names: The names of the extensions to load.
:type names: list(str)
:param invoke_on_load: Boolean controlling whether to invoke the
object returned by the entry point after the driver is loaded.
:type invoke_on_load: bool
:param invoke_args: Positional arguments to pass when invoking
the object returned by the entry point. Only used if invoke_on_load
is True.
:type invoke_args: tuple
:param invoke_kwds: Named arguments to pass when invoking
the object returned by the entry point. Only used if invoke_on_load
is True.
:type invoke_kwds: dict
:param name_order: If true, sort the loaded extensions to match the
order used in ``names``.
:type name_order: bool
:param propagate_map_exceptions: Boolean controlling whether exceptions
are propagated up through the map call or whether they are logged and
then ignored
:type propagate_map_exceptions: bool
"""
def __init__(self, namespace, names,
invoke_on_load=False, invoke_args=(), invoke_kwds={},
name_order=False, propagate_map_exceptions=False):
self._init_attributes(
namespace, names, name_order=name_order,
propagate_map_exceptions=propagate_map_exceptions)
extensions = self._load_plugins(invoke_on_load,
invoke_args,
invoke_kwds)
self._init_plugins(extensions)
@classmethod
def make_test_instance(cls, extensions, namespace='TESTING',
propagate_map_exceptions=False):
"""Construct a test NamedExtensionManager
Test instances are passed a list of extensions to use rather than
loading them from entry points.
:param extensions: Pre-configured Extension instances
:type extensions: list of :class:`~stevedore.extension.Extension`
:param namespace: The namespace for the manager; used only for
identification since the extensions are passed in.
:type namespace: str
:param propagate_map_exceptions: Boolean controlling whether exceptions
are propagated up through the map call or whether they are logged
and then ignored
:type propagate_map_exceptions: bool
:return: The manager instance, initialized for testing
"""
o = cls.__new__(cls)
names = [e.name for e in extensions]
o._init_attributes(namespace, names,
propagate_map_exceptions=propagate_map_exceptions)
o._init_plugins(extensions)
return o
def _init_attributes(self, namespace, names, name_order=False,
propagate_map_exceptions=False):
super(NamedExtensionManager, self)._init_attributes(
namespace, propagate_map_exceptions=propagate_map_exceptions)
self._names = names
self._name_order = name_order
def _init_plugins(self, extensions):
super(NamedExtensionManager, self)._init_plugins(extensions)
if self._name_order:
self.extensions = [self[n] for n in self._names]
def _load_one_plugin(self, ep, invoke_on_load, invoke_args, invoke_kwds):
# Check the name before going any further to prevent
# undesirable code from being loaded at all if we are not
# going to use it.
if ep.name not in self._names:
return None
return super(NamedExtensionManager, self)._load_one_plugin(
ep, invoke_on_load, invoke_args, invoke_kwds,
)