All this talk about stack frames and manipulating them at runtime has reminded me of one of my biggest gripes about Python. When I say "biggest gripe", I really mean "biggest surprise" or "biggest shame". That is, Python is very interactive and dynamic. However, when I am debugging Python, it seems to lose this. There is no way for me to effectively change a running program. Now with VC6, I can do this with C. Although it is slow and a little dumb, I can change the C side of my Python world while my program is running, but not the Python side of the world. Im wondering how feasable it would be to change Python code _while_ running under the debugger. Presumably this would require a way of recompiling the current block of code, patching this code back into the object, and somehow tricking the stack frame to use this new block of code; even if a first-cut had to restart the block or somesuch... Any thoughts on this? Mark.