# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# Copyright(C) 2013-2018 Max-Planck-Society
#
# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
# and financially supported by the Studienstiftung des deutschen Volkes.

from ..operators.scaling_operator import ScalingOperator
from .model import Model


class Variable(Model):
    """
    Changes MultiField to be a Variable model.
    Returns the MultiField.
    """
    def __init__(self, position):
        super(Variable, self).__init__(position)

        self._value = position
        self._gradient = ScalingOperator(1., position.domain)

    def at(self, position):
        return self.__class__(position)