KeyExtractor generic parameter makes conditional runtime handling difficult

[dpc]

In my app I'd like the user to have an option to rate-limit based on IP (if running in a standalone mode), or reverse proxy headers. However currently conditionally setting the extractor makes the types be incompatible.

Seems to me like either GovernorConfig should drop the K generic and Box key_extractor to Box<dyn KeyExtractor>, or at very least impl KeyExtractor for Box<T> where T: KeyExtractor (and maybe for Arc<T> too), to allow people to have unified GovernorConfig<Box<dyn KeyExtractor>> that can have runtime-conditional key extractor.

[dpc]

Oh, I tried to impl Arc<dyn KeyExtractor> via newtype, and it doesn't work because : Clone, preventing it from being object safe.

[benwis]

Hmm, if my understanding of Arc and dyn is correct, that thing should be object safe, and Clone. Can you provide a minimal example? I'm also wondering if you've tried impl KeyExtractor.

[dpc]

: Clone implies : Sized which prevent the trait for being usable as dyn KeyExtractor.

BTW. I have worked it around.

[nyarly]

That said, an enum in tower-governor for KeyExtractor would be aces