Source code for espressomd.highlander
#
# Copyright (C) 2013-2018 The ESPResSo project
#
# This file is part of ESPResSo.
#
# ESPResSo 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.
#
# ESPResSo 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/>.
#
from functools import update_wrapper
[docs]class ThereCanOnlyBeOne(BaseException):
def __init__(self, cls):
self._cls = cls
def __str__(self):
return "There can only be one instance of '{}' at any time.".format(self._cls)
[docs]def highlander(klass):
klass.highlander_created = False
def cls_init(self, *args, **kwargs):
"__init__ method by the highlander decorator."
if self.__class__.highlander_created:
raise ThereCanOnlyBeOne(self.__class__)
self.__class__.highlander_created = True
def cls_init_call_orig(self, *args, **kwargs):
if self.__class__.highlander_created:
raise ThereCanOnlyBeOne(self.__class__)
self.__class__.highlander_created = True
self.__class__.__init_orig__(self, *args, **kwargs)
# override the __init__ method of the class to store the bool
# "highlander_created"
if hasattr(klass, '__init__'):
klass.__init_orig__ = klass.__init__
klass.__init__ = cls_init_call_orig
update_wrapper(cls_init_call_orig, klass.__init_orig__)
else:
klass.__init__ = cls_init
# override the __del__ method of the class
def cls_del(self):
"__del__ method by the highlander decorator."
self.__class__.highlander_created = False
def cls_del_call_orig(self):
cls_del(self)
self.__class__.__del_orig__(self)
if hasattr(klass, '__del__'):
klass.__del_orig__ = klass.__del__
klass.__del__ = cls_del_call_orig
update_wrapper(cls_del_call_orig, klass.__del_orig__)
else:
klass.__del__ = cls_del
return klass