[Urwid] Twisted version of generic_main_loop

[Ian Ward]

Ian Ward wrote:
> Walter Mundt wrote:
>> Ian Ward wrote:
>>> It's a good start.  I was hoping this could be done with
>>> get_input_descriptors[1] and get_input_nonblocking[2] instead of using
>>> threads.
>>>
>>> [1] http://excess.org/urwid/reference.html#Screen-get_input_descriptors
>>> [2] http://excess.org/urwid/reference.html#Screen-get_input_nonblocking
>> Done.  Also, this version adds a handle_reactor parameter.  If False, 
>> rather than looping the function simply returns a twisted Deferred that 
>> will trigger when the UI shuts down, whether via an ExitMainLoop call 
>> (callback True) or a different unhandled exception in one of the 
>> handlers passed in (errback).
> 
> Great!  That was fast, Walter :-)
> 
> A couple final suggestions: twisted_main_loop needs a docstring 
> explaining what you said above, and the code should be written in a way 
> that I can add it to main_loop.py even on systems without twisted 
> installed - either only import twisted.(...) inside the functions that 
> need those symbols, or handle the ImportError and make twisted_main_loop 
> send a helpful error message.
> 
> Ian

I have added your code with some modifications to the hg repo:
https://excess.org/hg/urwid/file/2bd2ab311547/urwid/main_loop.py

Some initial testing suggests that the error handling isn't quite 
behaving properly.  I tried running:
     urwid.generic_main_loop(urwid.SolidFill('x'))
and compared it to:
     urwid.twisted_main_loop(urwid.SolidFill('x'))

The first one fails out when I press a key (solidfill can't handle 
keystrokes) or ^C, but the second one doesn't quite do the same thing.

Ian