The biggest thing I’ve run into where I really want self-referential types is for work that I want to perform once and then cache, while still needing access to the original data.
An example: parsing a cookie header to get cookie names and values.
In that case, I settled on storing indexes indicating the ranges of each key and value instead of string slices, but it’s obviously a bit more error prone and hard to read. Benchmarking showed this to be almost twice as fast as cloning the values out into owned strings, so it was worth it, given it is in a hot path.
I do wish it were easier though. I know there are ways around this with Pin, but it’s very confusing IMO, and still you have to work with pointers rather than just having a &str.
An example: parsing a cookie header to get cookie names and values.
In that case, I settled on storing indexes indicating the ranges of each key and value instead of string slices, but it’s obviously a bit more error prone and hard to read. Benchmarking showed this to be almost twice as fast as cloning the values out into owned strings, so it was worth it, given it is in a hot path.
I do wish it were easier though. I know there are ways around this with Pin, but it’s very confusing IMO, and still you have to work with pointers rather than just having a &str.