casual_logger

A logger used when practicing the example 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 {} files.", 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:

Part	Name	Description	Default
`./`		Working directory
		only.
`tic-tac-toe`	Prefix	Editable.	`default`
`-2020-07-12`	StartDate	Auto generated.
`.log`	Suffix	Editable.	`.log`
`.toml`	Extension	Editable.	`.toml`

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

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;
    }

    // ...
}

Logger Properties

Name	Description	Default
`retention_days`	After this number of days,	`7`
	the file will be deleted.
`level`	Used to switch between	`Trace`
	write and non-write.

Example of retention_days:

retention_days is 2.
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.

Example of level:

There are 7 log levels.
- |Fatal< Error < Warn < Notice < Info < Debug <Trace|
- |<-- Small ------------------------------ Large -->|
- |<-- Concise -------------------------- Verbose -->|
- |<-- Low Level --------------------- High level -->|
- |<-- High priority --------------- Low priority -->|

Level	Examle of use.
`Fatal`	If the program cannot continue.
`Error`	I didn't get the expected result,
	so I'll continue with the other method.
`Warn`	It will be abnormal soon,
	but there is no problem and you can ignore it.
	For example:
	(1) He reported that it took longer to access
	than expected.
	(2) Report that capacity is approaching the limit.
`Notice`	It must be enabled in the server production
	environment.
	Record of passing important points correctly.
	We are monitoring that it is working properly.
`Info`	Report highlights.
	Everything that needs to be reported regularly in
	the production environment.
`Debug`	It should be in a place with many accidents.
	This level is disabled in production environments.
	Leave it in the source and enable it for
	troubleshooting.
	Often, this is the production level of a desktop
	operating environment.
`Trace`	Not included in the distribution.
	Remove this level from the source after using it
	for debugging.
	If you want to find a bug in the program,
	write a lot.