Re: [jokosher-devel] Modifying a pipeling while in PLAYING state

[Laszlo Pandy <laszlok2 gmail com>]

Lukas wrote:
>  Also what's going to happen to the
> GP. 

The GP is being scrapped. It doesn't do anything except change the 
state, but we now have a way around that.

> I still think its a good idea to have all the pipeline code in one
> spot, to keep things organised and such.

This is kinda hard to do. Having *all* the pipeline code in the same 
spot would mean combining instruments, events, effects, playback and 
recording all in one class. That would be a little much.

As for putting all the pipeline state changes in one place, they are 
already supposed to be. Only Project.play(), Project.record(), 
Project.stop() and TransportManager.play() should change the pipeline 
state. Everyone else should learn to deal with a pipeline in any state.

What we really have to do is start enforcing a pipeline policy, and 
review everyone else's patches to make sure they keep it. So far our 
tentative policy is everything should expect the pipeline to be in 
PAUSED or PLAYING (they're basically the same thing) but still be able 
to handle the occasional READY. This means:

1) The pipeline must always be in a playable state. If you unlink 
something, immediately link it to something else. Currently we do a 
whole lot of preparation for playing in Project.play() which will no 
longer work.
2) Whenever you unlink two elements, you must block the pad first so it 
doesn't complain about a non linking error. I still have to figure out 
the details of this, but it should be something like pad.set_blocked(True).

Laszlo