python_plugins.py

import abc
import importlib

class Plugins(abc.ABCMeta):
   plugins = dict()
   def __new__(metaclass, name, bases, namespace):
       cls = abc.ABCMeta.__new__(
           metaclass, name, bases, namespace)
       if isinstance(cls.name, str):
           metaclass.plugins[cls.name] = cls
       return cls
    
   @classmethod
   def get(cls, name):
       if name not in cls.plugins:
           print('Loading plugins from plugins.%s' % name)
           importlib.import_module('plugins.%s' % name)
       return cls.plugins[name]

    
class PluginBase(metaclass=Plugins):
    @property
    @abc.abstractmethod
    def name(self):
      raise NotImplemented()
      
      
class plugin(PluginBase):
  name = 'plugin1'