[Bf-committers] Re: listener object

[Toni Alatalo]

> Ton Roosendaal wrote:
> > I don't think an "Always scrptlink" is the way to go... we should keep  
> > things fully event based in Blender's UI.

but, as said in the posts that followed (by Martin & Campbell),
that was not about the UI, but having an invisible daemon running in 
Blender, serving requests coming from outside (e.g. information about 
what material some object is using etc., if i understood correctly).

i agree that the 'always' scriptlink feels strange, and liked Martin's
idea of a 'onIncomingSockedData' scriptlink or something like that. as far
as i can see the only benefit of the 'always' one would be that no socket
handling would be needed on the C side of Blender, which would only need
to activate the scripts from the mainloop using some sort of timer
perhaps. that is how it has always worked on the game engine side, where
there actually is an 'always' sensor, that has been used to implement
network servers within Blender too - doing all the networking in Python 
only.

first i thought that the 'always' scriptlink might be useful for other 
kind of background-processing python scripts too, but those probably are 
better off as event-driven (perhaps with SceneChanged or something like 
that added if needed, but that's irrelevant to this discussion).

did something come out of this already, what did Martin&co choose to do?
.. oh just noticed that he's posting follow-ups to bf-python, i'll be 
looking there and wont post more here anymore either.

> > Would it be possible for Python to add callbacks instead? Meaning, it  
> > assigns to an external program the means to insert events in the main  
> > queue, which is then being handled by another script. Could also be a  
> > means to plugin input devices.

i guess that is possible. and as Martin and others saw, sockets are an ok 
way for it. just the mechanism to enable bpython scripts to receive socket 
connections is needed, for example by making either the 'always' / 
'onTimer' or 'onIncomingSocketData' scriptlinks. right?

> > -Ton-

~Toni

> > On 6 May, 2005, at 13:21, Martin DeMello wrote:
> > 
> >> On 5/6/05, Martin DeMello <martindemello at gmail.com> wrote:
> >>
> >>> I'd like to add a "listener" object to blender, to allow a script to
> >>> be triggered by an external program writing to a socket. (Not
> >>> necessarily proposing this be added to blender proper, but it would be
> >>> very useful for my own copy.) Is this an intrinsically dangerous idea?
> >>> (i.e. could it cause instability or crashes in blender?) If not, how
> >>> would I go about doing it? (i.e., where in the code should I be
> >>> looking to add something like this?)
> >> Also, antont suggested on IRC that an 'always' scriptlink that
> >> activated once every timer tick would be another nice way to
> >> accomplish this. The triggered python script could then poll the
> >> socket.
> >>
> >> martin