Remember the break from Numeric to numpy / scipy.core? Matplotlib managed to port OK, which was not small feat. The fact that you could do lots of try/excepts

Remember the break from Numeric to numpy / scipy.core? Matplotlib managed to port OK, which was not small feat. The fact that you could do lots of try/excepts helped: try: import Numeric as np newaxis = np.NewAxis ... else: import numpy as np newaxis = np.newaxis I think that was about 10 years ago. It took ~5 years to gain acceptance. Python 3 is < 2.5 years old (3.0 final was Dec, 2008), so it's not doing that badly. The big problem seems to be whether both versions can run off the same source base, even with some voodoo (i.e. defining print functions, etc).