casual_logger

A logger used when practicing the sample programs.
Only write to file, rotate by date.
Not for hard users.

At first, Disclaim

It differs from the standard Rust log interface.
Ignore performance for ease of use.

At second, Overall view

Your code:

use casual_logger::{Level, Log, LOGGER};

fn main() {
    let remove_num = if let Ok(mut logger) = LOGGER.lock() {
        // Do not call 'Log::xxxxx()' in this code block.
        //
        // Set file name.
        //
        // All: 'tic-tac-toe-2020-07-12.log.toml'
        // Prefix: 'tic-tac-toe'
        // StartDate: '-2020-07-12' automatically.
        // Suffix: '.log' - To be safe, include a word that
        //         clearly states that you can delete the file.
        // Extention: '.toml'
        //
        // If you don't like the .toml extension, leave the
        // suffix empty and the .log extension.
        logger.set_file_name("tic-tac-toe", ".log", ".toml");

        logger.retention_days = 2;
        // The higher this level, the more will be omitted.
        //
        // |<-- Low Level ----------------------- High level -->|
        // |<-- High priority ----------------- Low priority -->|
        // |Fatal < Error < Warn < Notice < Info < Debug < Trace|
        logger.level = Level::Trace;
        // Remove old log files. This is determined by the
        // StartDate in the filename.
        logger.remove_old_logs()
    } else {
        0
    };
    Log::noticeln(&format!("Remove file count={}", remove_num));

    Log::infoln(
        "Hello, world!!
こんにちわ、世界！！",
    );

    if Log::enabled(Level::Info) {
        let x = 100; // Time-consuming preparation, here.
        Log::infoln(&format!("x is {}.", x));
    }

    Log::trace("A,");
    Log::traceln("B,");
    Log::debug("C,");
    Log::debugln("D,");
    Log::info("E,");
    Log::infoln("F,");
    Log::notice("G,");
    Log::noticeln("H,");
    Log::warn("I,");
    Log::warnln("J,");
    Log::error("K,");
    Log::errorln("L,");
    Log::fatal("M,");
    Log::fatalln("N!");
}

Output ./default-2020-07-12.log.toml auto generated:

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=1"]
Notice = "Remove file count=0\r\n"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=2"]
Info = """
Hello, world!!
こんにちわ、世界！！\r\n
"""

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=3"]
Info = "x is 100.\r\n"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=4"]
Trace = "A,"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=5"]
Trace = "B,\r\n"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=6"]
Debug = "C,"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=7"]
Debug = "D,\r\n"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=8"]
Info = "E,"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=9"]
Info = "F,\r\n"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=10"]
Notice = "G,"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=11"]
Notice = "H,\r\n"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=12"]
Warn = "I,"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=13"]
Warn = "J,\r\n"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=14"]
Error = "K,"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=15"]
Error = "L,\r\n"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=16"]
Fatal = "M,"

["Now=2020-07-12 00:49:17&Pid=19548&Thr=ThreadId(1)&Seq=17"]
Fatal = "N!\r\n"

At third, Description

Code:

use casual_logger::{Level, Log, LOGGER};

At the timing of the first writing, a file with a
time stamp in its name is automatically generated.
For example: ./tic-tac-toe-2020-07-12.log.toml

Description:

./ - Working directory only.
tic-tac-toe - Prefix. Editable. Default: default.
-2020-07-12 - StartDate. Auto generated.
.log - Suffix. Editable. Default: .log.

Suffix to be safe, include a word that
clearly states that you can delete the file.

.toml - Extension. Editable. Default: .toml.

If you don't like the .toml extension, leave
the suffix empty and the .log extension.

Set up, Code:

fn main() {
    if let Ok(mut logger) = LOGGER.lock() {
        logger.set_file_name("tic-tac-toe", ".log", ".toml");
        logger.retention_days = 2;
        logger.level = Level::Trace;
    }

    // ...
}

Description of retention_days:

For example, retention_days is 2. Default: 7.
Today is 2020-07-12.
The ./default-2020-07-09.log.toml file will be deleted.
The ./default-2020-07-10.log.toml remains.
Delete old files by date in filename.

Description of level:

There are 7 log levels. Default: Trace.
- Fatal < Error < Warn < Notice < Info < Debug < Trace.
Example:
- Log::info("Hello, world!!");
- Log::infoln("Hello, world!!");
- if Log::enabled(Level::Info) {Log::infoln("Hello!");}