self

[holger krekel]

[me]
  IOW you cannot successfully wrap or inherit a dictionary type and pass it 
  to exec/eval :-(
 
[David Bolen]
  Yes, I did also find a posting by Guido (didn't save the reference,
  but it was via a google search) where he seemed to indicate that
  subclassing list/dict other than add additional functionality (rather
  than override core operations like lookups) could be problematic -
  presumably because of cases like this where the special Python-exposed
  functions are used.  The message was during one of the later betas of
  2.2, so I don't know if the viewpoint changed before final release.

everything is a google-search away if you know the right codewords :-)
I don't in this case, though ...

anyway, if you call dictionary methods from python you can intercept.
But either generally c-level code ignores python-overriden methods 
or only eval/exec "optimizes" them out. I presume that this is for
speed reasons but there may lurk conceptual reasons as well. Who knows?

  holger