Suggest using "rosys.on_startup()" instead of "app.on_startup()"

[AndyPermaRobotics]

Hello together,

I figured out that there are two callbacks, that a rosys script can use for startup initialization code.
One is from nicegui app.on_startup() and one is rosys.on_startup().
Actually app.on_startup() an rosys.on_startup() are connected internally (see rosys.py).

But there is (at least) one possible pitfall:
If I want to set rosys.config.simulation_speed programmatically, the change is overwritten if I do it in the app.on_startup() callback, because the nicegui callback is invoked before persistence.restore() is called in the startup() routine of rosys see here.

I stumbled over it then I tried to set the simulation_speed to 1.0 in the production mode, but the script used the persisted simulation_speed of my previous tests.

I don't see a need to use app.on_startup() instead of rosys.on_startup() therefore I suggest to encourage the usage of rosys.on_startup() in the rosys examples and the documentation.

[rodja]

Sure. The examples should use rosys.on_startup(). And maybe we can even monkey patch app.on_startup to warn in a RoSys app?

[falkoschindler]

I tried monkey-patching app.on_startup. But NiceGUI is using it internally, e.g. for ui.timer, so we get warnings even if there is no app.on_startup in user-code. We could inspect the call stack, but that's getting pretty messy I think. I tend to simply fix the examples and documentation without monkey-patching the code.

[rodja]

@falkoschindler just created the nice PR #46 to improve documentation in this regard.