def import_class(import_str):
"""Returns a class from a string including module and class."""
mod_str, _sep, class_str = import_str.rpartition('.')
try:
__import__(mod_str)
return getattr(sys.modules[mod_str], class_str)
except (ImportError, ValueError, AttributeError), exc:
LOG.debug(_('Inner Exception: %s'), exc)
raise exception.ClassNotFound(class_name=class_str, exception=exc)
def get_filter_classes(filter_class_names):
"""Get filter classes from class names."""
classes = []
for cls_name in filter_class_names:
obj = utils.import_class(cls_name)
if _is_filter_class(obj):
classes.append(obj)
elif type(obj) is types.FunctionType:
# Get list of classes from a function
classes.extend(obj())
else:
raise exception.ClassNotFound(class_name=cls_name,
exception='Not a valid scheduler filter')
return classes
def get_matching_classes(self, loadable_class_names):
"""Get loadable classes from a list of names. Each name can be
a full module path or the full path to a method that returns
classes to use. The latter behavior is useful to specify a method
that returns a list of classes to use in a default case.
"""
classes = []
for cls_name in loadable_class_names:
obj = importutils.import_class(cls_name)
if self._is_correct_class(obj):
classes.append(obj)
elif inspect.isfunction(obj):
# Get list of classes from a function
for cls in obj():
classes.append(cls)
else:
error_str = 'Not a class of the correct type'
raise exception.ClassNotFound(class_name=cls_name,
exception=error_str)
return classes
