[Urwid] MainLoop's pipe is not removed after pipe data ends.

Ian Ward ian at excess.org
Tue Apr 10 15:03:48 EDT 2012

On Fri, Apr 6, 2012 at 8:29 AM, Andrew Wu
> --- urwid_bak/main_loop.py    2012-04-03 19:20:16.000000000 +0800
> +++ urwid/main_loop.py    2012-04-06 20:18:20.000000000 +0800
> @@ -186,8 +186,7 @@
>              data = os.read(pipe_rd, PIPE_BUFFER_READ_SIZE)
>              rval = callback(data)
>              if rval is False:
> -                self.event_loop.remove_watch_file(watch_handle)
> -                os.close(pipe_rd)
> +                self.remove_watch_pipe(pipe_wr)
>          watch_handle = self.event_loop.watch_file(pipe_rd, cb)
>          self._watch_pipes[pipe_wr] = (watch_handle, pipe_rd)

That does seem to make more sense.

Now that I'm looking at it though I don't like the interface.  As in
your test code you need to add a comment on "return False" to
understand what is actually going to happen.

Using something like this might be an improvement:

  return "close pipe"

There is also the problem of leaking fds.  The write fd is not closed
by remove_watch_pipe (as documented).  Maybe an optional parameter to
close both ends would help?

Now it seems like there shouldn't be a special way to close a pipe
with a handler's return value (getting too complicated)



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