Added paramNotifyChanged() to let apps notify the core when they modify the value of a parameter programmatically

[ntamas]

This function intends to cater for the use-case when an app modifies the value of a parameter using paramSetInt(), paramSetFloat() or some similar mechanism (i.e. not externally via a CRTP packet but internally). Currently these functions do not call the callbacks associated to the parameter if there is one; paramNotifyChanged() allows the app code to trigger the callback programmatically.

Another option would be to change paramSetInt(), paramSetFloat() and similar functions to call the callback, but I don't know what other implications this change may have so I went for the surgical option instead.

[ataffanel]

Good finding, I think the fact that the callback was not called by the internal API function is a bug.

I would say that calling the paramNotifyChanged function from paramSetInt and paramSetFloat is the right things to do: the internal param API should work as much as possible like the external API to avoid bug and surprises.

I am not sure the notify function should be pubic in that case though.

[krichardsson]

I agree with @ataffanel
Sounds reasonable that the callback is called also when a parameter is set from an app in the FW

[ntamas]

Okay, I'll change the PR then, give me a sec :)

[ntamas]

First iteration. Maybe the call to paramNotifyChanged() could actually also be pushed down to paramSet(), but then the callbacks would also be called in persistentParamFromStorage() - do we want that or not?

[krichardsson]

Oh, that is a good question! And a bit scary because it touches on the infinitely complex topic of initialization. The initialization process/sequence is slightly undefined at the moment and in my opinion we really should shape it up to clearly define the expected behavior. For how I would say that we do not call the callback when setting parameters from persisted values.

At the moment there is no case where we have a persistent parameter with a callback so we can decide on what ever solution we want I guess.

[ataffanel]

I agree, one idea of stored parameter was to 'simulate' the behavior of default value, in that sense not calling the callback for stored parameter sounds like the right behavior.

[krichardsson]

Thanks!

[ntamas]

Note that the title of the PR became misleading now that paramNotifyChanged() is not a public function any more. The upside is that apps don't need to do anything explicitly now.