Singleton objects

import lib.DatabaseLayer as db

from lib.Config    import Configuration as conf

from lib.Singleton import Singleton

# Constants

UNREACHABLE   = -1

  def validateUser(self, user, pwd):

    return WRONG_CREDS

class AuthenticationHandler:

class AuthenticationHandler(metaclass=Singleton):

  def __init__(self):

    self.methods = []

    self._load_methods()

import lib.DatabaseLayer as db

from lib.Config    import Configuration as conf

from lib.Config    import ConfigReader

from lib.Singleton import Singleton

class PluginManager():

class PluginManager(metaclass=Singleton):

  def __init__(self):

    self.plugins = {}

class Singleton(type):

  _instances = {}

  def __call__(cls, *args, **kwargs):

    if cls not in cls._instances:

      cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)

    return cls._instances[cls]