log-derive
A Rust macro to part of the log facade that auto generates loggings for functions output.
Usage
Add this to your Cargo.toml:
[dependencies]
log-derive = "0.3"
log = "0.4"
and for Rust Edition 2015 add this to your crate root:
#[macro_use]
extern crate log_derive;
extern crate log;In Rust Edition 2018 you can simply do:
use log_derive::logfn;After that all you need is to add the according macro above a function that,
either returns an output or receive an input that implements the Debug trait.
Examples
#[logfn(Err = "Error", fmt = "Failed Sending Packet: {:?}")]
fn send_hi(addr: SocketAddr) -> Result<(), io::Error> {
let mut stream = TcpStream::connect(addr)?;
stream.write(b"Hi!")?;
Ok( () )
}#[logfn(Trace)]
#[logfn_inputs(Info)]
fn test_log(a: u8) -> String {
(a*2).to_string()
}#[logfn(Trace, fmt = "testing the num: {:?}")]
fn test_log(a: u8) -> String {
(a*2).to_string()
}Output
The output of the fibonacci example:
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 5)
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 4)
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 3)
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 2)
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 1)
17:15:24 [ INFO] fibonacci() -> 1
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 0)
17:15:24 [ INFO] fibonacci() -> 1
17:15:24 [ INFO] fibonacci() -> 2
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 1)
17:15:24 [ INFO] fibonacci() -> 1
17:15:24 [ INFO] fibonacci() -> 3
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 2)
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 1)
17:15:24 [ INFO] fibonacci() -> 1
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 0)
17:15:24 [ INFO] fibonacci() -> 1
17:15:24 [ INFO] fibonacci() -> 2
17:15:24 [ INFO] fibonacci() -> 5
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 3)
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 2)
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 1)
17:15:24 [ INFO] fibonacci() -> 1
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 0)
17:15:24 [ INFO] fibonacci() -> 1
17:15:24 [ INFO] fibonacci() -> 2
17:15:24 [TRACE] (1) fibonacci: [examples/fibonacci.rs:16] fibonacci(n: 1)
17:15:24 [ INFO] fibonacci() -> 1
17:15:24 [ INFO] fibonacci() -> 3
17:15:24 [ INFO] fibonacci() -> 8
If you expand the output of the #[logfn] macro the resulting code will look something like this:
fn fibonacci(n: u32) -> u32 {
let result = (move || match n {
0 => 1,
1 => 1,
_ => fibonacci(n - 1) + fibonacci(n - 2),
})();
log::log!(log::Level::Info, "fibonacci() -> {}", result);
result
}If the function returns a Result it will match through it to split between the Ok LogLevel and the Err LogLevel
The expansion of the #[logfn_inputs] macro will look something like this:
fn fibonacci(n: u32) -> u32 {
log::log!(log::Level::Info, "fibonacci(n: {:?})", n);
match n {
0 => 1,
1 => 1,
_ => fibonacci(n - 1) + fibonacci(n - 2),
}
}Of course the log! macro will be expanded too and it will be a bit more messy.
Note
The log_ts feature will fail your compilation in a no-std enviroment.
it can only be used where std is available. (as it uses std::time::Instant)