nolog-plain logger

A non-colored version of the simple nolog logger for writing to a file.

If you need colored output, please refer to the nolog crate.

20 lines of code with 0 deps.
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. You can modify the code to disable this. See section "If you don't need to disable logging on a release build".
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-plain as a dependency for logging to a file

In Cargo.toml:

toml nolog-plain = "0.1.0"

Create a logger.rs like this (You can copy to your project and make changes to this code, improve and extend it):

```rust /* ---------------------------------------------------------------------------- MIT License

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. ---------------------------------------------------------------------------- */ use std::fs::OpenOptions; use std::io::{BufWriter, Write}; use std::path::PathBuf;

pub use nolog_plain::{crit, debug, error, info, trace, warn /* writelog */}; // We don't import writelog because we want to override it --- ^^^^^^^^

[rustfmt::skip] #[macroexport] #[cfg(debugassertions)] macro_rules!

writelog { ( $msg:expr ) => { log($msg) } } // ^^^ // function log instead of println macro.

pub struct LogFile;

impl LogFile { pub fn path() -> PathBuf { PathBuf::from("log.txt") } }

[rustfmt::skip]

pub fn log(msg: String) { let path = LogFile::path(); let openfile = |path| { OpenOptions::new() .create(true) .write(true) .append(true) .open(&path) }; if let Ok(file) = openfile(path) { let mut buf = BufWriter::new(file); writeln!(buf, "{msg}").ok(); buf.flush().ok(); }; } ```

main.rs could be like this:

```rust

[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;

use crate::logger::*; // ^^^^^^^^^ // It must be imported in each module in which we will use logging.

use std::io; use std::io::prelude::*; use std::fs::OpenOptions;

fn main() -> io::Result<()> { let path = LogFile::path(); let mut file = OpenOptions::new() .read(true) .write(true) .create(true) .truncate(true) //^^^^^^^ truncate the file to 0 length if it already exists. .open(&path)?;

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}");

let mut contents = String::new();
file.read_to_string(&mut contents)?;
println!("-- In {path:?} --");
println!("{contents}");

/* Output:
-- In "log.txt" --
TRCE: text 42,42,42 [src/main.rs 29:5]
DEBG: text 42,42,24 [src/main.rs 30:5]
INFO: text 42,24,42 [src/main.rs 31:5]
WARN: text 42,a,422 [src/main.rs 32:5]
ERRO: text 42,42,42 [src/main.rs 33:5]
CRIT: text 42,42,42 [src/main.rs 34:5]
*/

Ok(())

} ```

Using nolog-plain directly

The same thing, only in Cargo.toml we do not add nolog-plain as a dependency and in logger.rs we copy the entire code of this library (all 20 lines):

```rust /* ---------------------------------------------------------------------------- MIT License

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

[rustfmt::skip] #[macroexport] #[cfg(debugassertions)] macro_rules!

trace { ( $($msg:expr),* ) => { writelog!(format!("TRCE: {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }

[rustfmt::skip] #[macroexport] #[cfg(debugassertions)] macro_rules!

debug { ( $($msg:expr),* ) => { writelog!(format!("DEBG: {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }

[rustfmt::skip] #[macroexport] #[cfg(debugassertions)] macro_rules!

info { ( $($msg:expr),* ) => { writelog!(format!("INFO: {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }

[rustfmt::skip] #[macroexport] #[cfg(debugassertions)] macro_rules!

warn { ( $($msg:expr),* ) => { writelog!(format!("WARN: {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }

[rustfmt::skip] #[macroexport] #[cfg(debugassertions)] macro_rules!

error { ( $($msg:expr),* ) => { writelog!(format!("ERRO: {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }

[rustfmt::skip] #[macroexport] #[cfg(debugassertions)] macro_rules!

crit { ( $($msg:expr),* ) => { writelog!(format!("CRIT: {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }

[rustfmt::skip] #[macroexport] #[cfg(not(debugassertions))] macro_rules! trace { ( $($msg:expr),* ) => () }

[rustfmt::skip] #[macroexport] #[cfg(not(debugassertions))] macro_rules! debug { ( $($msg:expr),* ) => () }

[rustfmt::skip] #[macroexport] #[cfg(not(debugassertions))] macro_rules! info { ( $($msg:expr),* ) => () }

[rustfmt::skip] #[macroexport] #[cfg(not(debugassertions))] macro_rules! warn { ( $($msg:expr),* ) => () }

[rustfmt::skip] #[macroexport] #[cfg(not(debugassertions))] macro_rules! error { ( $($msg:expr),* ) => () }

[rustfmt::skip] #[macroexport] #[cfg(not(debugassertions))] macro_rules! crit { ( $($msg:expr),* ) => () }

[rustfmt::skip] #[macroexport] #[cfg(debugassertions)] macro_rules!

writelog { ( $msg:expr ) => { log($msg) } } // ^^^ // function log instead of println macro.

pub struct LogFile;

impl LogFile { pub fn path() -> PathBuf { PathBuf::from("log.txt") } }

[rustfmt::skip]

Now you have a logger and no new dependencies.

If you don't need to disable logging on a release build

This will make the code even shorter. Use code like this:

```rust /* ---------------------------------------------------------------------------- MIT License

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

[rustfmt::skip] #[macroexport] macrorules!

trace { ( $($msg:expr),* ) => { writelog!(format!("TRCE: {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }

[rustfmt::skip] #[macroexport] macrorules!

debug { ( $($msg:expr),* ) => { writelog!(format!("DEBG: {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }

[rustfmt::skip] #[macroexport] macrorules!

info { ( $($msg:expr),* ) => { writelog!(format!("INFO: {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }

[rustfmt::skip] #[macroexport] macrorules!

warn { ( $($msg:expr),* ) => { writelog!(format!("WARN: {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }

[rustfmt::skip] #[macroexport] macrorules!

error { ( $($msg:expr),* ) => { writelog!(format!("ERRO: {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }

[rustfmt::skip] #[macroexport] macrorules!

crit { ( $($msg:expr),* ) => { writelog!(format!("CRIT: {} [{} {}:{}]", format!($($msg),*), file!(), line!(), column!())) } }

[rustfmt::skip] #[macroexport] macrorules!

writelog { ( $msg:expr ) => { println!("{}", $msg) } } ```