[pypy-dev] Running Python in reverse

Alexander Schliep schliep at molgen.mpg.de
Tue Jan 11 16:51:54 CET 2005

On Fri, 7 Jan 2005 hpk at trillke.net (holger krekel) wrote:
> ...
> Yes, i see the problem.  At EuroPython 2004 there also was Michael Salib
> who also presented his wish to have a "time warp" debugger that allows
> to arbitrarily move within execution time of your program and see all
> the state.  And IIRC, we have been discussing this between PyPy developers

This sounds like the same general idea.

> ...
> Rightfully so.  I wouldn't call it "run backwards" though but to jump
> arbitrarily in execution and object states.

The visualization would look like running backwards; technically you are

> Yes, although for debugging in general there is the problem of
> "side effects" like dealing with files & sockets, databases etc.pp.

Fortunately, this is not a problem for me.

> Well, the question is if we could tackle the "History Space" (working
> title) at some sprint and you would attend and we would together incorporate

It will be really difficult for me to attend sprints, I already travel way
too much. I'd be glad though to start to code towards extending Gato.

Does it make it a lot of sense to run the whole tkinter app in pypy,
or would we just have an embedded pypy-interpreter for the algorithm?
Do you have suggestions how to setup the whole thing?

Right now I just execfile the algorithm under debugger control. The
algorihms calls the visualisation commands as side effects when
doing interesting stuff (put a vertex on a queue). The debugger
calls the idle_task etc. to keep the GUI alive, whenever something

> the functionality into your application for the fun of it. I imagine
> a "time slider" that you can arbitrarily move forward and backward
> ...

Basically like VCR controls. I'd add "run backwards" or so.


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