rfc1155.py 文件源码

def clone(self, value=univ.noValue, **kwargs):
        """Clone this instance.

        If *value* is specified, use its tag as the component type selector,
        and itself as the component value.

        :param value: (Optional) the component value.
        :type value: :py:obj:`pyasn1.type.base.Asn1ItemBase`
        :return: the cloned instance.
        :rtype: :py:obj:`pysnmp.proto.rfc1155.NetworkAddress`
        :raise: :py:obj:`pysnmp.smi.error.SmiError`:
            if the type of *value* is not allowed for this Choice instance.
        """
        cloned = univ.Choice.clone(self, **kwargs)
        if value is not univ.noValue:
            if isinstance(value, NetworkAddress):
                value = value.getComponent()
            elif not isinstance(value, IpAddress):
                # IpAddress is the only supported type, perhaps forever because
                # this is SNMPv1.
                value = IpAddress(value)
            try:
                tagSet = value.tagSet
            except AttributeError:
                raise PyAsn1Error('component value %r has no tag set' % (value,))
            cloned.setComponentByType(tagSet, value)
        return cloned

    # RFC 1212, section 4.1.6:
    #
    #    "(5)  NetworkAddress-valued: `n+1' sub-identifiers, where `n'
    #          depends on the kind of address being encoded (the first
    #          sub-identifier indicates the kind of address, value 1
    #          indicates an IpAddress);"