Re: [Python-ideas] 80 character line width vs. something wider

May 20, 2009


      "Cesare Di Mauro"
<cesare.dimauro@a-tono.com> writes:
...
...
From threading.py:
That's a perfect example of doing too much in one function, thank you.
Here's a first draft refactor for both making it easier to keep track
of, and reducing the indentation as an added benefit::

class Thread(_Verbose):
    def _prepare_bootstrap(self):
        self.__ident = _get_ident()
        self.__started.set()
        _active_limbo_lock.acquire()
        _active[self.__ident] = self
        del _limbo[self]
        _active_limbo_lock.release()
        if __debug__:
            self._note("%s.__bootstrap(): thread started", self)

        if _trace_hook:
            self._note("%s.__bootstrap(): registering trace hook", self)
            _sys.settrace(_trace_hook)
        if _profile_hook:
            self._note("%s.__bootstrap(): registering profile hook", self)
            _sys.setprofile(_profile_hook)

    def _bootstrap_run(self):
        try:
            self.run()
        except SystemExit:
            if __debug__:
                self._note("%s.__bootstrap(): raised SystemExit", self)
        except:
            self._unhandled_exception()
        else:
            if __debug__:
                self._note("%s.__bootstrap(): normal return", self)
        finally:
            # Prevent a race in
            # test_threading.test_no_refcycle_through_target when
            # the exception keeps the target alive past when we
            # assert that it's dead.
            self.__exc_clear()

    def _unhandled_exception(self):
        if __debug__:
            self._note("%s.__bootstrap(): unhandled exception", self)
        # If sys.stderr is no more (most likely from interpreter
        # shutdown) use self.__stderr.  Otherwise still use sys (as in
        # _sys) in case sys.stderr was redefined since the creation of
        # self.
        if _sys:
            _sys.stderr.write("Exception in thread %s:\n%s\n" %
                              (self.name, _format_exc()))
        else:
            # Do the best job possible w/o a huge amt. of code to
            # approximate a traceback (code ideas from
            # Lib/traceback.py)
            exc_type, exc_value, exc_tb = self.__exc_info()
            try:
                print>>self.__stderr, (
                    "Exception in thread " + self.name +
                    " (most likely raised during interpreter shutdown):")
                print>>self.__stderr, (
                    "Traceback (most recent call last):")
                while exc_tb:
                    print>>self.__stderr, (
                        '  File "%s", line %s, in %s' %
                        (exc_tb.tb_frame.f_code.co_filename,
                            exc_tb.tb_lineno,
                            exc_tb.tb_frame.f_code.co_name))
                    exc_tb = exc_tb.tb_next
                print>>self.__stderr, ("%s: %s" % (exc_type, exc_value))
            # Make sure that exc_tb gets deleted since it is a memory
            # hog; deleting everything else is just for thoroughness
            finally:
                del exc_type, exc_value, exc_tb

    def _limbo_lock_stop(self):
        with _active_limbo_lock:
            self.__stop()
            try:
                # We don't call self.__delete() because it also
                # grabs _active_limbo_lock.
                del _active[_get_ident()]
            except:
                pass

    def __bootstrap_inner(self):
        try:
            self._prepare_bootstrap()
            self._bootstrap_run()
        finally:
            self._limbo_lock_stop()

-- 
 \         “Apologize, v. To lay the foundation for a future offense.” |
  `\                   —Ambrose Bierce, _The Devil's Dictionary_, 1906 |
_o__)                                                                  |
Ben Finney