[LV2] Add/remove/change ports from practical view ?

Sven Jaehnichen sjaehn at jahnichen.de
Wed Jun 3 05:24:19 PDT 2020

Am 30.05.20 um 14:49 schrieb David Robillard:

> I'm open to this relaxation if nobody else has a problem with it.  From
> an ultra strict perspective it's breaking the spec in that hosts would
> be required to deal with a new situation, but it doesn't seem like one
> that should cause much trouble, and in practice probably already
> doesn't as you noted.

Thank you to mention this. This already caused some headache to me. 
Maybe the addition of a short notice ("Host developers are asked ...") 
may point into the desired direction without breaking the specs?

> Why would an "unused" port ever have
> existed at all?  This seems like a pretty esoteric case to me.

Control ports. Reserved in a early version of a plugin. But not used in 
the plugin binary. I agree, this wasn't a good strategy. The question 
is: keep the ports until there will be (maybe) a use for it?

> A more programmer-ey example than automation and stuff to think about
> is script bindings.  If a plugin had a "gain" port, and I was using
> nice script bindings and had some script that did plugin.gain = 60,
> what happens when there is no gain port anymore?  A crash, probably.
> That's not good.  Just as with libraries, compatibility matters for
> plugin interfaces.

Scripts are a good point. I didn't have them in my focus, yet. Although 
it doesn't make much sense to use unused ports in a script. Anyway, a 
crash would be even worse. This argues for keep unused ports.


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