Re: [Flightgear-devel] Generic Autopilot Rework Proposal

[James T. <ja...@fl...>]

> On 11 Jan 2022, at 12:44, Benedikt Hallinger <be...@ha...> wrote:
> 
> James, that would be nice, I already have some use case in mind :)

I’m hacking this up, some comments:

	- the config option is called ‘property-path’, if anyone has a strong alternative idea, please let me know

	- if property-path is set, ‘property’ is ignored

	- changes to the property-path re-resolve the node at that time (via a listener), and I don’t poll for the property appearing later, since property lookups are slow and autopilot components run fast : so you can’t specify a non-existing node path and then create the node later. I don’t see a huge issue here but maybe it’s awkward for Nasal? But in that case an fdm-initialized script can just write to the path property (triggering the listener) and everything will work.

	- if the property path doesn’t resolve to a valid node, the input will be marked as disabled: this feels sensible since it allows cascading inputs as we do with conditions (conditions still work *as well*, it’s a logical AND) : so it’s easy to fall back to a value if no valid property is found

	- if there is a <value> defined, we will set it on the node pointed to by property-path : I’m not sure about this, but it’s also what inputs do when they have a <value> *and* a <property>

	(if anyone has a reason not to do this, I can be easily convinced to change it….)

Going to add unit-tests for all this of course, before pushing.

Kind regards,
James