Meta programming question

[Jeff Epler]

The changes are not large, if I understand what the OP is asking for.
However, they have a performance impact on the "common case".

In Python, a dict subclass's __setitem__ is never invoked when
evaluating bytecode.  With a change to just a few opcodes (STORE_GLOBAL,
STORE_NAME), this can be rectified, so that
    >>> exec "x = 3" in d
will call d.__setitem__("x", 3), and you can do whatever you need to do
on "assignment".

The patch was never finished, and never added to the sf patch manager.
You can visit the python-dev thread at 
    http://mail.python.org/pipermail/python-dev/2002-October/029761.html

Jeff