Description
I would like to use slog inside of a bootloader, meaning that I need to be able to turn off logging when necessary to save binary size, and I also want to avoid relying on static memory (and slog seems to be the only logging library that I have found that does not have this baked in).
However, I fear that if I am to use the default Logger<Arc<SendSyncRefUnwindSafeDrain>>, then some optimizations will be missed, especially when I want to fully turn off logging.
Trying to use Logger::root_typed, I quickly came to an issue: it's impossible for a function to give the correct trait requirements on the drain for Logger to be used:
fn main() {
let drain = obtain_drain();
let logger = Logger::root_typed(&drain, slog::o!());
my_function(&logger);
}
// Unfortunately not sufficient:
fn my_function<D: SendSyncUnwindDrain>(logger: &Logger<D>) {
slog::info!(logger, "Hello world");
}The only way around this that I have found so far is to require the generic parameter D to implement slog::SendSyncUnwindDrain<Ok = (), Err = slog::Never>, which requires the use of the doc_hidden bottom type placeholder.
I think a very simple solution would be to provide a trait, Log, which would be implemented by Logger when the requirements for Logger::log are satisfied.
With it, the code above would simplify to fn my_function(logger: &impl slog::Log).
If the method on Log is called something other than log (say log_record), then such a change would only require a minor version bump, and Logger::log could be left as-is, with the macros calling Log::log_record directly (assuming that until now, slog::log! could only be used with a Logger).