[Python-3000] PEPs update (original) (raw)

Raymond Hettinger python at rcn.com
Fri May 11 18:22:57 CEST 2007

Thanks for taking time to review my code.

You welcome. And thanks for the continuing development effort.

Did you look through the PEP as well?

Yes.

In fact, I am half way done with implementing the change so that small BLists are memory efficient.

As the code continues to evolve, I'll continue to look at it. I look forward to seeing how far you can take this. Newly developed code always faces an uphill battle when compared to mature open-source.

I am not sure what aspect of the performance might be misunderstood. Just about everything is O(log n). Could you clarify your concern?

End-users (everyday Python programmers) need to be understand the performance intuitively and have a clear understanding of what is going on under-the-hood. Our existing data structures have the virtue of having a simple mental model (except for aspects of re-sizing and over-allocation which are a bit obscure).

Would it be useful if I created an experimental fork of 2.5 that replaces array-based lists with BLists, so that the performance penalty (if any) on existing code can be measured?

That would likely be an informative exercise and would assure that your code is truly interchangable with regular lists. It would also highlight the under-the-hood difficulties you'll encounter with the C-API.

That being said, it is a labor intensive exercise and the time might be better spent on tweaking the third-party module code and building a happy user-base.

Indeed, I wrote the BList because there were idioms that I wanted to use that were just not practical with an array-based list.

We ought to set up a page on the wiki for success stories with blist as a third-party module. In time, the Right Answer (tm) will become self-evident.

Raymond

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