[IPython-dev] Status of IPython+GUI+Threads+PyOS_InputHook

[Hans Meine]

On Sunday 08 February 2009 21:53:54 Gael Varoquaux wrote:
> I have given a lot of thought to this, and I believe that to avoid
> freezing, there is no other option than multiple processes.

I just wanted to chime in again and mention that this is also the approach we 
(the VIGRA developers, i.e. mainly Ullrich Köthe and me) took with our PyQt-
based interactive python terminal ('pyterm', not officially released, although 
some versions should be floating around the WWW).  I am not very fond of its 
actual code and state, but the basic design of separate front- and backend has 
paid out AFAICS.

Ulli had actually designed a very simple socket protocol between the two 
processes, with commands for communicating e.g. I/O and completions.
I think that that should better be factored out, i.e. one should have proxy 
objects that behave like their counterparts in the opposite processes, such 
that it becomes possible (or at least less work) to directly wire a frontend 
and backend in the same process, too.  (In the past, I needed this for easy 
embedding of the terminal widget in a Qt program of mine, with direct access 
to the embedding program's state.)

One big advantage of the separation was *proper* Ctrl-C handling.  The main 
disadvantage was that API was needed to access the frontend's UI from the 
backend; Ulli introduced this to be able to add menu entries from within the 
backend.

HTH,
  Hans