ryu/build/lib.linux-armv7l-2.7/ryu/services/protocols/bgp/operator/views/fields.py

   1 import importlib
   2 import inspect
   3
   4 import six
   5
   6
   7 class Field(object):
   8     def __init__(self, field_name):
   9         self.field_name = field_name
  10
  11     def get(self, obj):
  12         return getattr(obj, self.field_name)
  13
  14
  15 class RelatedViewField(Field):
  16     def __init__(self, field_name, operator_view_class):
  17         super(RelatedViewField, self).__init__(field_name)
  18         self.__operator_view_class = operator_view_class
  19
  20     @property
  21     def _operator_view_class(self):
  22         if inspect.isclass(self.__operator_view_class):
  23             return self.__operator_view_class
  24         elif isinstance(self.__operator_view_class, six.string_types):
  25             try:
  26                 module_name, class_name =\
  27                     self.__operator_view_class.rsplit('.', 1)
  28                 return class_for_name(module_name, class_name)
  29             except (AttributeError, ValueError, ImportError):
  30                 raise WrongOperatorViewClassError(
  31                     'There is no "%s" class' % self.__operator_view_class
  32                 )
  33
  34     def retrieve_and_wrap(self, obj):
  35         related_obj = self.get(obj)
  36         return self.wrap(related_obj)
  37
  38     def wrap(self, obj):
  39         return self._operator_view_class(obj)
  40
  41
  42 class RelatedListViewField(RelatedViewField):
  43     pass
  44
  45
  46 class RelatedDictViewField(RelatedViewField):
  47     pass
  48
  49
  50 class DataField(Field):
  51     pass
  52
  53
  54 class OptionalDataField(DataField):
  55     def get(self, obj):
  56         if hasattr(obj, self.field_name):
  57             return getattr(obj, self.field_name)
  58         else:
  59             return None
  60
  61
  62 class WrongOperatorViewClassError(Exception):
  63     pass
  64
  65
  66 def class_for_name(module_name, class_name):
  67     # load the module, will raise ImportError if module cannot be loaded
  68     m = importlib.import_module(module_name)
  69     # get the class, will raise AttributeError if class cannot be found
  70     c = getattr(m, class_name)
  71     return c