@util.positional(1)
def import_descriptor_loader(definition_name, importer=__import__):
  # Attempt to import descriptor as a module.
  if definition_name.startswith('.'):
    definition_name = definition_name[1:]
  if not definition_name.startswith('.'):
    leaf = definition_name.split('.')[-1]
    if definition_name:
      try:
        module = importer(definition_name, '', '', [leaf])
      except ImportError:
        pass
      else:
        return describe(module)

  try:
    # Attempt to use messages.find_definition to find item.
    return describe(messages.find_definition(definition_name,
                                             importer=__import__))
  except messages.DefinitionNotFoundError, err:
    # There are things that find_definition will not find, but if the parent
    # is loaded, its children can be searched for a match.
    split_name = definition_name.rsplit('.', 1)
    if len(split_name) > 1:
      parent, child = split_name
      try:
        parent_definition = import_descriptor_loader(parent, importer=importer)
      except messages.DefinitionNotFoundError:
        # Fall through to original error.
        pass
      else:
        # Check the parent definition for a matching descriptor.
        if isinstance(parent_definition, FileDescriptor):
          search_list = parent_definition.service_types or []
        elif isinstance(parent_definition, ServiceDescriptor):
          search_list = parent_definition.methods or []
        elif isinstance(parent_definition, EnumDescriptor):
          search_list = parent_definition.values or []
        elif isinstance(parent_definition, MessageDescriptor):
          search_list = parent_definition.fields or []
        else:
          search_list = []

        for definition in search_list:
          if definition.name == child:
            return definition

    # Still didn't find.  Reraise original exception.
    raise err
Find objects by importing modules as needed.
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/protorpc/protorpc/descriptor.py/import_descriptor_loader