What cool hacks can be done using sys.settrace?

Question

I love being able to modify the arguments the get sent to a function, using settrace, like :

import sys

def trace_func(frame,event,arg):
    va         


        

Answer 1

I don't have an exhaustively comprehensive answer but one thing I did with it, with the help of another user on SO, was create a program that generates the trace tables of other Python programs.