20 lines of code with 0 deps.
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 (there are the same 20 lines of code, but with coloring).
info!("{line_count} lines.");.[src/main.rs 15:5].[2022-07-10 06:49:33.646361181 UTC].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".log crate. As the project grows, it is possible
to migrate to an advanced logger (using the log crate facade)
without changing the code.stderr or file).
In Cargo.toml:
toml
nolog-plain = "0.2.1"
Download the examples below:
sh
git clone https://github.com/vglinka/nolog-plain
cd ./nolog-plain/
```sh
cargo run --example base
cargo run --example to-file
cargo run --example to-stderr
cargo run --example to-file-debug-plus-release
cargo run --example to-file-debug-plus-release --release
sh
cd ./examples/as-dep-to-file-timestamp-chrono/
cargo run
sh
cd ./examples/as-dep-to-file/
cargo run
```
logger.rs:
```rust /* ---------------------------------------------------------------------------- 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. ---------------------------------------------------------------------------- */
pub use nolog_plain::{crit, debug, error, info, trace, warn /* writelog */}; // We don't import writelog because we want to override it --- ^^^^^^^^
writelog { ( $msg:expr ) => { log($msg) } }
// ^^^
// function log instead of println macro.
use std::fmt::Arguments; use std::fs::OpenOptions; use std::io::{BufWriter, Write}; use std::path::PathBuf;
pub struct LogFile;
impl LogFile { pub fn path() -> PathBuf { PathBuf::from("log.txt") } }
pub fn log(msg: Arguments) { // ^^^^^^^^^ std::fmt::Arguments 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:
```rust mod logger;
use crate::logger::*; // ^^^^^^^^^ // It must be imported in each module in which we will use logging.
use std::fs::OpenOptions; use std::io; use std::io::prelude::*;
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(())
} ```
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
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. ---------------------------------------------------------------------------- */
trace { ( $($msg:expr),* ) => { writelog!(formatargs!("TRCE: {} [{} {}:{}]", formatargs!($($msg),*), file!(), line!(), column!())) } }
debug { ( $($msg:expr),* ) => { writelog!(formatargs!("DEBG: {} [{} {}:{}]", formatargs!($($msg),*), file!(), line!(), column!())) } }
info { ( $($msg:expr),* ) => { writelog!(formatargs!("INFO: {} [{} {}:{}]", formatargs!($($msg),*), file!(), line!(), column!())) } }
warn { ( $($msg:expr),* ) => { writelog!(formatargs!("WARN: {} [{} {}:{}]", formatargs!($($msg),*), file!(), line!(), column!())) } }
error { ( $($msg:expr),* ) => { writelog!(formatargs!("ERRO: {} [{} {}:{}]", formatargs!($($msg),*), file!(), line!(), column!())) } }
crit { ( $($msg:expr),* ) => { writelog!(formatargs!("CRIT: {} [{} {}:{}]", formatargs!($($msg),*), file!(), line!(), column!())) } }
writelog { ( $msg:expr ) => { log($msg) } }
// ^^^
// function log instead of println macro.
use std::fmt::Arguments; use std::fs::OpenOptions; use std::io::{BufWriter, Write}; use std::path::PathBuf;
pub struct LogFile;
impl LogFile { pub fn path() -> PathBuf { PathBuf::from("log.txt") } }
pub fn log(msg: Arguments) { // ^^^^^^^^^ std::fmt::Arguments 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(); }; } ```
Now you have a logger and no new dependencies.
For example, we will use chrono crate.
-- In "log.txt" --
[2022-07-10 06:49:33.646361181 UTC] TRCE: text 42,42,42 [src/main.rs 22:5]
[2022-07-10 06:49:33.646393648 UTC] DEBG: text 42,42,24 [src/main.rs 23:5]
[2022-07-10 06:49:33.646405179 UTC] INFO: text 42,24,42 [src/main.rs 24:5]
[2022-07-10 06:49:33.646415125 UTC] WARN: text 42,a,422 [src/main.rs 25:5]
[2022-07-10 06:49:33.646424722 UTC] ERRO: text 42,42,42 [src/main.rs 26:5]
[2022-07-10 06:49:33.646434216 UTC] CRIT: text 42,42,42 [src/main.rs 27:5]
See example code.
This will make the code even shorter:
```rust /* ---------------------------------------------------------------------------- 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. ---------------------------------------------------------------------------- */
trace { ( $($msg:expr),* ) => { writelog!(formatargs!("TRCE: {} [{} {}:{}]", formatargs!($($msg),*), file!(), line!(), column!())) } }
debug { ( $($msg:expr),* ) => { writelog!(formatargs!("DEBG: {} [{} {}:{}]", formatargs!($($msg),*), file!(), line!(), column!())) } }
info { ( $($msg:expr),* ) => { writelog!(formatargs!("INFO: {} [{} {}:{}]", formatargs!($($msg),*), file!(), line!(), column!())) } }
warn { ( $($msg:expr),* ) => { writelog!(formatargs!("WARN: {} [{} {}:{}]", formatargs!($($msg),*), file!(), line!(), column!())) } }
error { ( $($msg:expr),* ) => { writelog!(formatargs!("ERRO: {} [{} {}:{}]", formatargs!($($msg),*), file!(), line!(), column!())) } }
crit { ( $($msg:expr),* ) => { writelog!(formatargs!("CRIT: {} [{} {}:{}]", formatargs!($($msg),*), file!(), line!(), column!())) } }
writelog { ( $msg:expr ) => { println!("{}", $msg) } } ```
README.md and examples.format!() have been replaced with
invocation format_args!() because format_args!() avoids heap
allocations. All examples have been updated. The use of format_args!()
has affected the code for writing to a file. Now std::fmt::Arguments
is used instead of String.
See example.README.md and examples.README.md and examples.