Log Derive

log-derive provides a simple attribute macro that facilitates logs as part of the log facade Right now it contains two macros logfn, logfn_inputs these macros are only for functions but still have a lot of power.

Use

The basic use of these macros is by putting one or both of them on top of the function like this: #[logfn(INFO)]

The logfn macro is used to log the output of the function and logfn_inputs is used to log the inputs. Please notice, the arguments being logged must implement the Debug trait. (i.e. logfn requires the output to be Debug and logfn_inputs require the inputs to be Debug)

The macros will accept all log levels provided by the log facade. In logfn if the function returns a Result type the macro will accept the following additional attributes: (ok = "LEVEL") and (err = "LEVEL") this can provide different log levels if the function failed or not.

By default the macro uses the following formatting to print the message: logfn: ("FUNCTION_NAME() => {:?}", return_val) logfn_inputs: "FUNCTION_NAME(a: {:?}, b: {:?})", a, b) This can be easily changed using the fmt attribute: #[logfn(LEVEL, fmt = "Important Result: {:}") which will accept format strings similar to println!.

Examples

use log_derive::{logfn, logfn_inputs};

# #[derive(Debug)]
struct Error;
# #[derive(Debug)]
struct Success;
# #[derive(Debug)]
enum Status { Alive, Dead, Unknown }

#[logfn(Warn)]
#[logfn_inputs(Info, fmt = "Checking if {:?} is alive")]
fn is_alive(person: &Person) -> Status {
# use Response::*;
# use Status::*;
match person.ping() {
Pong => Status::Alive,
Timeout => if person.is_awake() {
Unknown
} else {
Dead
}
}
}

#[logfn_inputs(Info)]
#[logfn(ok = "TRACE", err = "ERROR")]
fn call_isan(num: &str) -> Result<Success, Error> {
if num.len() >= 10 && num.len() <= 15 {
Ok(Success)
} else {
Err(Error)
}
}

#[logfn(INFO, fmt = "a + b = {}")]
#[logfn_inputs(Trace, fmt = "adding a: {:?} and b: {:?}")]
fn addition(a: usize, b: usize) -> usize {
a + b
}

#[logfn_inputs(Info)]
#[logfn(ok = "TRACE", log_ts = true)]
fn time_this(num: &str) -> Result<Success, Error> {
if num.len() >= 10 && num.len() <= 15 {
std::thread::sleep(Duration::from_secs(1));
Ok(Success)
} else {
Err(Error)
}
}

# enum Response {Pong, Timeout}
# #[derive(Debug)]
# struct Person;
# impl Person {fn ping(&self) -> Response {Response::Pong}fn is_awake(&self) -> bool {true}}
# use std::time::Duration;