singleton

simple_singleton.py

def singleton(cls):
  """
  Simple singleton implementation.
  
  Usage:
  
  @singleton
  class A:
    pass
  
  a = A()
  b = A()
  # a == b
  """
    instance = None

    def class_instanciation_or_not(*args, **kwargs):
        nonlocal instance
        if not instance:
            instance = cls(*args, **kwargs)
        return instance
return class_instanciation_or_not