term.py 文件源码

def __neg__(self):
        """
        >>> (- Literal(1))
        rdflib.term.Literal(%(u)s'-1', datatype=rdflib.term.URIRef(%(u)s'http://www.w3.org/2001/XMLSchema#integer'))
        >>> (- Literal(10.5))
        rdflib.term.Literal(%(u)s'-10.5', datatype=rdflib.term.URIRef(%(u)s'http://www.w3.org/2001/XMLSchema#double'))
        >>> from rdflib.namespace import XSD
        >>> (- Literal("1", datatype=XSD.integer))
        rdflib.term.Literal(%(u)s'-1', datatype=rdflib.term.URIRef(%(u)s'http://www.w3.org/2001/XMLSchema#integer'))

        >>> (- Literal("1"))
        Traceback (most recent call last):
          File "<stdin>", line 1, in <module>
        TypeError: Not a number; rdflib.term.Literal(%(u)s'1')
        >>>
        """

        if isinstance(self.value, (int, long, float)):
            return Literal(self.value.__neg__())
        else:
            raise TypeError("Not a number; %s" % repr(self))