Class registry via metaclassing

metaclass_registry.py

class MetaRegistry(type):

  class_registry = {}

  def __new__(meta, name, bases, class_dict):
    cls = type.__new__(meta, name, bases, class_dict)
    if name not in meta.class_registry:
      meta.register_class(meta.class_registry, cls)
    return cls

  @staticmethod
  def register_class(registry, target_class):
    registry[target_class.__name__] = target_class