_base.py 文件源码

def _invoke_callbacks(self):
        for callback in self._done_callbacks:
            try:
                callback(self)
            except Exception:
                LOGGER.exception('exception calling callback for %r', self)
            except BaseException:
                # Explicitly let all other new-style exceptions through so
                # that we can catch all old-style exceptions with a simple
                # "except:" clause below.
                #
                # All old-style exception objects are instances of
                # types.InstanceType, but "except types.InstanceType:" does
                # not catch old-style exceptions for some reason.  Thus, the
                # only way to catch all old-style exceptions without catching
                # any new-style exceptions is to filter out the new-style
                # exceptions, which all derive from BaseException.
                raise
            except:
                # Because of the BaseException clause above, this handler only
                # executes for old-style exception objects.
                LOGGER.exception('exception calling callback for %r', self)