A few concerns:
There doesn't seem to be a debug or trace log level. This is
quite a useful thing to have once your program is deployed.
I don't like the returning by ref for log methods. For example,
it seems like you can do: log(5 < 4, "This is a test log") = new
StdIOLogger();
It could potentially be useful to return the Logger so you can
chain calls and such, but it should not be possible to set the
logger by assigning the result of a log call.
The simple act of logging a message is very verbose right now:
log(LogLevel.trace, "Creating new pool") is a lot of boiler
plate. I'd prefer something like log.trace("Creating new pool")
and log("Creating new pool") where the latter would use opCall to
forward to the default log level. If it's intentional that you
can assign the result of log, this also helps that because log =
new StdIOLogger would be possible (log being a property that
returns a Logger, and so a setter could be made), but
log("Creating new pool") = new StdIOLogger() would not be.
There's a lot of suggestions for things like network logging, but
I think this is far beyond the scope of the module, and the sheer
amount of different ways of doing it means people will likely
write their own anyways. For example, synchronous vs
asynchronous, what protocol to use, authentication, client data,
encryption, etc.
