'Construction of :class:`.RelationshipProperty.Comparator`
is internal to the ORM\'s attribute mechanics.'

def __init__(self, prop, parentmapper, adapt_to_entity=None, of_type=None):

    self.prop = prop
    self._parentmapper = parentmapper
    self._adapt_to_entity = adapt_to_entity
    if of_type:
        self._of_type = of_type
