[Python-Dev] Module renaming and pickle mechanisms (original) (raw)

glyph at divmod.com glyph at divmod.com
Sun May 18 01:44:38 CEST 2008

On 10:22 pm, greg.ewing at canterbury.ac.nz wrote:

When I brought this up earlier, various people assured me that it wasn't a problem in practice. I think we're seeing one situation here where it is a problem.

Just my two cents here - experience has taught me that it's definitely a problem in practice. One big problem with pickle is that it's even difficult to tell when or how much your persistence format depends on your application code. For example, if you're pickling a dict that is supposed to map strings to integers, but you have a bug which accidentally ends up using a string subclass instead, it can be very difficult to figure out that this ever happened.

pickletools is really neat, and can help with this problem once you're stuck, but it's a better idea to use a more explicit persistence mechanism in the first place if you can.

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