[Python-Dev] Saving the hash value of tuples (original) (raw)

Raymond Hettinger python at rcn.com
Mon Apr 3 05:23:58 CEST 2006

I've found out that the hash value of tuples isn't saved after it's calculated. With strings it's different: the hash value of a string is calculated only on the first call to hash(string), and saved in the structure for future use. Saving the value makes dict lookup of tuples an operation with an amortized cost of O(1). [...] I will be happy to send a patch, if someone shows interest. Regardless of whether anyone shows interest, please submit a patch! Then post the URL back here. That way if someone gets interested in the future, your code is still available.

FWIW, I think that is not a good idea. Guido shot it down for good reason. Once a patch is loaded, the question will continually resurface every few months and waste everyone's time re-hashing the issue. We have bigger dragons to slay.

Raymond

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