[transaction] initialize transaction data and state related attribute.
There is not reason to not explicitly declare and initialize attribute in
Transaction.__init__. This change requires the introduction of a
Transaction.clear() method to get ride of some wicked ``AttributeError`` based
logic.
# pylint: disable=W0614,W0401
# copyright 2003-2010 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of CubicWeb.
#
# CubicWeb is free software: you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option)
# any later version.
#
# CubicWeb is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with CubicWeb. If not, see <http://www.gnu.org/licenses/>.
from warnings import warn
warn('moved to cubicweb.dataimport', DeprecationWarning, stacklevel=2)
from cubicweb.dataimport import *