> Yes & no. What we could do is have the dictionary and have shadow 
> variables. Change the dict, and the shadow variables change too. Think of 
> these variables as caching the result of key lookups. While we can't look 
> in the dictionary in interrupt context, if we do it right, we _can_ look 
> at the shadow variables. Put another way, as long as we don't do it wrong, 
> we can read the shadow variables.
> 
> This does mean we need to know when the dictionary changes (as long as the 
> driver gets called, not hard). Also, it means that the dictionary can't 
> contain state that needs gathering at interrupt context. Though I doubt 
> anyone would use a properties dictionary for that. :-)

what's the point to have a dictionary at all in addition to the
"shadow variables"?

YAMAMOTO Takashi