Re: [Flightgear-devel] Generic Autopilot Rework Proposal

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

> On 10 Jan 2022, at 15:36, Josh Davidson <jos...@gm...> wrote:
> 
> I am not sure, if you can do such a thing in the confines of propertyrule configuration, to "take" the property value from the string and then read from it. Do you have any suggestion about it? (Nasal is not an option, the rate of update is too slow, which would cause problems in the control loop)
> 

There’s two options there:

	- add a property-source-path feature to InputValue, which is the common input stage for all the property-filter / AP modules

	(quite easy, and likely useful for a few other things)

	- use a Nasal helper to watch for the source path changing (likely, almost never), and copy the values to /autopilot/inputs, and update an ALIAS


(This is close to what the EGPWS does: it defines  input/ and output/ subdirs, and these correspond closely to the real-world connections on the device. So in this case the main AP rules would reference /autopilot/inputs/altitude-ft, and the Nasal helper would ensure whichever property is pointed to by config/altitude-ft-prop-path is aliased to /autopilot/input/altitude.

Kind regards,
James