Ideally that would be a great feature to have.  I think the key is to avoid a lot of internal hacking of individual objects, like the code Nilay is removing in this patch.  I'm not sure what the best final solution is.  Could we dyncamically call the python scripts during simulation?  Could we somehow directly incorporate the power model components into the sim object hierarchy?

I think it is straight forward to invoke python scripts during simulation.  We do it
all the time, don't we?  We can have pseudo instructions in the application that
moves us back into the python hierarchy and then invokes the script.  Or else, we can
have periodic intervals at which the simulator would return to python and compute the
power consumption for the interval gone by.  I think both these can be realized with 
some understanding how things work currently.  I think we should let the users decide
how they want to do it.

I am not opposed this patch going in as is, but there are definitely reasons to avoid the C++ -> Python -> C++ ping-ponging.

#1 Performance. We have seen massive drops when using Python to do the power equation calculations. Of course it depends on granularity, but even in very realistic cases it is a massive problem.

#2 Dependency on Python. We are about to push a number of patches that allows gem5 to operate entirely without Python. This is important when using it hosted in other simulation frameworks e.g. SystemC or SST.