> _sentinel = object() > _val = _sentinel > def val(): > if _val is _sentinel: > # Calculate _val > return _val > > seems entirely sufficient for this case. Write a custom decorator if you use > the idiom often enough to make it worth the effort.
I did some timings with this as part of my timings above and found it to be significantly slower than lru_cache with the C extension. I had to add `nonlocal` to get `_val` to resolve, which I think kills performance a bit. I agree with the premise though, it might be worth exploring. > There is a more elegant and faster approach if you use a non-data > descriptor instead of a property or a lru_cache. If you use a non-data > descriptor property, you can even get rid of subsequent function calls. > I dumped some example code in a gist, > https://gist.github.com/tiran/da7d4c43d493c5aa7d7abc4d8a0678a6 Thank you! That's an interesting and great idea. It's faster, but not faster than lru-cache with the C extension. I'll investigate further. -- https://mail.python.org/mailman/listinfo/python-list
