Source code for espressomd.highlander

#
# Copyright (C) 2013-2019 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): # pylint: disable=unused-argument "__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