I considered to use the concept of flags, but then rejected it, simply because it adds another layer of abstraction, which is great in certain cases, but also increases the overall complexity.

In my case i need hardly any properties which span over more than one state, so i prefer to keep thinks simple for now. It's the constant struggle to have enough, but not to much abstraction...

But thanks for the hint, i'll keep that in mind.

Hmmm as you can provide every state with a specific tag, I don't see why to develop a less generic, less efficient concept which will be hard to make work for submachines. Am I missing something?

...

...

2) Is a const version of "get_state" possible ? And how?

Sure. My mistake. Will be fixed in 1.47. Would you mind opening a ticket so I don't forget it?

done, ticket #5253. Now i'am looking forward to 1.47 ;-)

Thanks. Regards, Christophe