Python werkzeug 模块，LocalProxy() 实例源码

def schemas(self):
        from werkzeug import LocalProxy

        def get_schemas():
            if not getattr(self, '_schemas', None):
                self.connect()
                try:
                    from .schemas import Schemas
                    self._schemas = Schemas(self._sqlalchemy_metadata)
                except ImportError:
                    logger.warning('cannot import Schemas, perhaps sqlalchemy is not up to date')
            return self._schemas
        return LocalProxy(get_schemas)