instance creatiion as an "event"

[Arthur]

I am trying to re-engineer, as lightly as possible, a Python app I 
wrote, to be make it more functional when used at the interactive prompt.

The only thing I seem to be missing is some kind of "hook" to trigger a 
general update cycle of all existing class instances upon the creation 
of a new class instance at the interactive prompt

The ideas I come up with to explore do not seem very straight forward - 
though some variation of one or another of them will probably work. But 
am generally weak on introspection issues and am wondering, before 
embarking done a crooked road:

Am I missing a something straight forward.

Ideas appreciated.

Art