Source code for core.singlobj

# 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 Lesser General Public License for more details.
#
# Copyright (c) 2015 Reishin <hapy.lestat@gmail.com>


class Singleton(object):

  def __init__(self, decorated):
    self._decorated = decorated

  def get_instance(self, *args, **kwargs):
    """
     Returns instance of the class if any present, or create new one

    :param args: arguments for class constructor
    :param kwargs: kwargs for class constructor
    :return: instance of the class
    """
    if '_instance' in dir(self):
      return self._instance
    else:
      self._instance = self._decorated(*args, **kwargs)
      return self._instance

  def __call__(self):
    raise TypeError('Singletons must be accessed through `get_instance()`.')

  def __instancecheck__(self, inst):
    return isinstance(inst, self._decorated)


class SingletonObject(object):
  def get_instance(self, *args, **kwargs):
    return self