require_loaded.py

def _require_loaded(method):
    """Wrapper for an instance method to allow lazy loading."""

    @functools.wraps(method)
    def wrapped_method(self, *args, **kwargs):
        """Wrapped version of an instance method which requires loaded.

        If the instance value of loaded is not True, then this will
        reload before calling the method.
        """
        if not self.loaded:
            self.reload()
        return method(self, *args, **kwargs)

    return wrapped_method