Sort by key

[vigna]

Feature suggestion: a version of the sort method with by_key, similar to sort_by_key for slices. This would avoid in many situations to have to define a struct containing a key and a value, when maybe tuples are sufficient.

[nessex]

Thanks for the suggestion!

Actually, I played with having a sort_by_key a long time ago. The reason I didn't include it originally is because I couldn't get it to work without having it significantly slow things down. All these radix sort libraries are really fragile, a very small change in the inner hot loops can have orders of magnitude impact on the final performance. If I recall correctly, the issue here had something to do with the compiler's ability to inline the key function.

I'll take a look in the next few days, and see if anything has changed. There have been a bunch of compiler changes in the last few years and maybe something has improved there to allow this without the performance penalty.

[vigna]

I don't need it anymore as I have created a struct and implemented RadixKey, but if it doesn't come without a performance penalty I think it would be a great feature.