nolog 0.1.0

Simple logger. 20 lines of code, 0 deps. Automatically disabled in the release build.
Documentation

nolog logger

20 lines of code with 0 deps.

  • Colored output.
  • Support for named format arguments info!("{line_count} lines.");.
  • Displays the location of the code [src/main.rs 15:5].
  • Automatically disabled in the release build cargo run --release.
  • Same syntax as log crate. As the project grows, it is possible to migrate to an advanced logger (using the log crate facade) without changing the code.
  • Can be built into the project directly instead of as a dependency.
  • Uses Rust's built-in macros.
  • Easy to modify to redirect log output (to stderr or file).
  • MIT License.

nolog

Using nolog

Create a logger.rs file with the following content (this is the complete library code):

/* ----------------------------------------------------------------------------
MIT License

Copyright (c) 2022 Vadim Glinka

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
---------------------------------------------------------------------------- */

#[rustfmt::skip] #[macro_export] #[cfg(debug_assertions)] macro_rules!
trace { ( $($msg:expr),* ) => { writelog!(format!("\x1B[34mTRCE:\x1B[0m {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }
#[rustfmt::skip] #[macro_export] #[cfg(debug_assertions)] macro_rules!
debug { ( $($msg:expr),* ) => { writelog!(format!("\x1B[36mDEBG:\x1B[0m {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }
#[rustfmt::skip] #[macro_export] #[cfg(debug_assertions)] macro_rules!
info { ( $($msg:expr),* )  => { writelog!(format!("\x1B[32mINFO:\x1B[0m {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }
#[rustfmt::skip] #[macro_export] #[cfg(debug_assertions)] macro_rules!
warn { ( $($msg:expr),* )  => { writelog!(format!("\x1B[33mWARN:\x1B[0m {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }
#[rustfmt::skip] #[macro_export] #[cfg(debug_assertions)] macro_rules!
error { ( $($msg:expr),* ) => { writelog!(format!("\x1B[31mERRO:\x1B[0m {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }
#[rustfmt::skip] #[macro_export] #[cfg(debug_assertions)] macro_rules!
crit { ( $($msg:expr),* )  => { writelog!(format!("\x1B[35mCRIT:\x1B[0m {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }

#[rustfmt::skip] #[macro_export] #[cfg(not(debug_assertions))] macro_rules! trace { ( $($msg:expr),* ) => () }
#[rustfmt::skip] #[macro_export] #[cfg(not(debug_assertions))] macro_rules! debug { ( $($msg:expr),* ) => () }
#[rustfmt::skip] #[macro_export] #[cfg(not(debug_assertions))] macro_rules! info  { ( $($msg:expr),* ) => () }
#[rustfmt::skip] #[macro_export] #[cfg(not(debug_assertions))] macro_rules! warn  { ( $($msg:expr),* ) => () }
#[rustfmt::skip] #[macro_export] #[cfg(not(debug_assertions))] macro_rules! error { ( $($msg:expr),* ) => () }
#[rustfmt::skip] #[macro_export] #[cfg(not(debug_assertions))] macro_rules! crit  { ( $($msg:expr),* ) => () }

#[rustfmt::skip] #[macro_export] #[cfg(debug_assertions)] macro_rules!
writelog { ( $msg:expr ) => { println!("{}", $msg) } }

main.rs could be like this:

#[macro_use]
mod logger;
//  ^^^^^^
//  Must go higher in the list than the modules
//  in which it will be used.
//  Macro import in modules below is not needed.
mod other;

fn main() {
    let a = 42;
    trace!("text {a},{a},{a}");
    debug!("text {a},{},{}", a, 24);
    info!("text {},{},{}", a, 24, "42");
    warn!("text {a},{},{}", 'a', "422");
    error!("text {a},{a},{}", a);
    crit!("text {a},{a},{a}");

    /* Output:
    TRCE: text 42,42,42 [examples/to-stderr.rs 55:5]
    DEBG: text 42,42,24 [examples/to-stderr.rs 56:5]
    INFO: text 42,24,42 [examples/to-stderr.rs 57:5]
    WARN: text 42,a,422 [examples/to-stderr.rs 58:5]
    ERRO: text 42,42,42 [examples/to-stderr.rs 59:5]
    CRIT: text 42,42,42 [examples/to-stderr.rs 60:5]
    */
}

Now you have a logger and no new dependencies.

Redirect output

To redirect output to stderr you need to add a single 'e' character to the writelog macro so that instead of println!() it becomes eprintln!(). See full example.

Write log to file: See full example.

Using nolog as a dependency

Although this logger was created to be used directly in small projects, you can also use it as a dependency.

In Cargo.toml:

nolog = "0.1.0"

In main.rs:

use nolog::*;

OR

use nolog::{crit, debug, error, info, trace, warn, writelog};

OR

#[macro_use]
pub extern crate nolog;

See full example.

Example

git clone https://github.com/vglinka/nolog

cargo run --example base
cargo run --example to-stderr
cargo run --example to-file