from yams.buildobjs import ComputedRelation, EntityType, RelationDefinition

from cubicweb.schema import RRQLExpression

class Subject(EntityType):

    pass

class Object(EntityType):

    pass

class relation(RelationDefinition):

    subject = 'Subject'

    object = 'Object'

class computed(ComputedRelation):

    rule = 'S relation O'

    __permissions__ = {'read': (RRQLExpression('S is ET'),)}