[pulseaudio-discuss] [PATCH 4/6] core: add message handler

[Tanu Kaskinen]

On Sat, 2017-10-21 at 22:00 +0200, Georg Chini wrote:
> On 03.10.2017 14:58, Tanu Kaskinen wrote:
> > 
> > > > Also, it's questionable why the list-handlers command is implemented
> > > > with the messaging API in the first place. It's core functionality, so
> > > > why is it not implemented using the normal introspection API?
> > > 
> > > Two reasons:
> > > 
> > > a) It's much simpler than using the introspection API
> > 
> > Ok, but didn't we agree earlier that the messaging API is only meant
> > for modules, and new core features shall be added using the existing
> > API conventions? The rationale, if you've forgotten it, was that it's
> > annoying for application developers if the core API uses inconsistent
> > conventions and introspection functionality needs to be searched from
> > two different places.
> > 
> > I might accept it if you put the client-facing bits in the
> > introspection API, but use the messaging system behind the scenes. If
> > you want pursue that route, I'd like get an ok from Arun as well. This
> > is not only about the list-handlers message, it's about all future core
> > features.
> > 
> > Another possibility is to deprecate the whole introspection API and
> > reimplement it using the messaging API, but you probably don't want to
> > take such a big project.
> > 
> > > b) We should at least have one example in the code
> > > which shows how a message handler is implemented.
> > 
> > It's certainly good to have an example now so that we can discuss how
> > the message parameter serialization is supposed to work, but I don't
> > think we need to apply that example to master. I hope we'll have some
> > other example by the time 12.0 is released (IIRC, you plan to add a
> > message handler to module-loopback), but it's not a big deal if there
> > are no examples.
> > 
> 
> Finally I found some time to work again on the message patches.
> 
> There is a third reason why I think getting the message handlers
> should be implemented using the message API:
> The message delivers information about the message API itself
> and the information should be accessible via that API.
> 
> So is it OK if I keep the message handler implementation (provided
> that the handler returns a more "machine readable" format)? Or will
> you reject it?

I think it's ok to keep it.

I have a related request: could you implement "pactl list message-
handlers"? The point of that would be to have nicer formatting than the
raw message reply.

-- 
Tanu

https://www.patreon.com/tanuk