class Backend(object): def __init__(self, opt): if 'plugin' not in opt: raise ValueError("no plugin selected") self.params = opt; self.backend = Plugin().load("plugins/Backend_"+opt['plugin']+".py") self.backend.constructor(self.params) def alreadyExist(self, key): res = self.backend.alreadyExist(key); if not isinstance(res, bool): raise TypeError('issues with the plugin: '+self.params['plugin']); else: return res; def put(self, key, obj): self.backend.put(key, obj);