sandboxing/running python code line by line

Question

I\'d love to be able to do something like these two are doing:

Inventing on principle @18:20 , Live ClojureScript Game Editor

If you don\'t wanna check the v

Answer 1

Update: After my initial success with this technique, I switched to using the ast module as described in my other answer.

sys.settrace() seems to work really well. I took the hacks question you mentioned and Andrew Dalke's article and got this simple example working.

import sys

def dump_frame(frame, event, arg):
    print '%d: %s' % (frame.f_lineno, event)
    for k, v in frame.f_locals.iteritems():
        print '    %s = %r' % (k, v)
    return dump_frame

def main():
    c = 0
    for i in range(3):
        c += i

    print 'final c = %r' % c

sys.settrace(dump_frame)

main()

I had to solve two problems to get this working.

1. The trace function has to return itself or another trace function if you want to continue tracing.
2. Tracing only seems to begin after the first function call. I originally didn't have the main method, and just went directly into a loop.

Here's the output:

9: call
10: line
11: line
    c = 0
12: line
    i = 0
    c = 0
11: line
    i = 0
    c = 0
12: line
    i = 1
    c = 0
11: line
    i = 1
    c = 1
12: line
    i = 2
    c = 1
11: line
    i = 2
    c = 3
14: line
    i = 2
    c = 3
final c = 3
14: return
    i = 2
    c = 3
38: call
    item = 
    selfref = 
38: call
    item = 
    selfref =