Re: [libvirt] [RFC 0/7] Warn at runtime when deprecated features are used

On Thu, 2018-10-04 at 14:13 +0100, Daniel P. Berrangé wrote: > I think we're largely missing the bigger picture here. Configuring > guests, and using libvirt APIs in general, can be very complicated. > > We provide basic API contract docs, and a crude XML schema reference, > but this is woefully insufficient. There's very little telling apps > about the big picture way to configure things / implement tasks. > > We're missing a good developer guide where you'd give info to apps > devs about how to effectively use libvirt, so it is no surprise that > apps do things that are sub-optimal. Providing better docs to app > devs would be far more useful than deprecation warnings which have > minimal contextual guidance. I agree that having better documentation would help, and we should definitely work towards that goal. However, I'm fairly confident trying to address issues through documentation only will not be enough to get applications off problematic API usage: people mentioned several times elsewhere in the thread how they think *emitting warnings* itself wouldn't be enough, and developers would only take notice once the application breaks for good! How is documentation going to be effective? Who would look at documentation periodically just to make sure they're not using features that have since been deprecated? I know I don't do that for any of libvirt's dependencies, but if I started getting warnings I'd certainly take notice. Unless users are nagged about it during usage and developers are nagged about it during development, usage of problematic APIs will never go away.