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Logging::Simple - Simple debug logging by number, with customizable labels and formatting

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    use Logging::Simple;

    my $log = Logging::Simple->new(name => 'whatever'); # name is optional

    $log->_4("default level is 4, we'll only print levels 4 and below");

    # change level


    # log only a single level


    # disable all levels


    # log to a file

    $log->_0("this will go to file");
    $log->file(0); # back to STDOUT

    # log to a "memory file"

    my $memfile;

    # don't print, return instead

    my $log_entry = $log->_2("print disabled");

    # send in your own log entry labels for the levels. They will be mapped
    # 0 through 7

    $log->labels([qw(emerg alert crit error warn notice info debug)]);

    # using a child log

    my $log = Logging::Simple->new(name => 'main');
    $log->_0("parent log");


    sub testing {
        my $log = $log->child('testing()');
        $log->_4("child log");
    [2016-04-21 16:31:30.039][lvl 0][main] parent log
    [2016-04-21 16:31:30.040][lvl 4][main.testing()] child log


Lightweight (core-only) and very simple yet flexible debug tool for printing or writing to file log type entries based on a configurable level (0-7).

Instead of named log facility methods, it uses numbers instead, preventing you from having to remember name to number mapping.

It provides the ability to programmatically change which output tags to display, provides the ability to create descendent children, easily enable/disable file output, levels, display etc. with the ability to provide custom labels.

Logging entry format

By default, log entries appear as such, with a timestamp, the name of the facility, the name (if previously set) and finally the actual log entry message.

    [2016-03-17 17:01:21.959][lvl 6][whatever] example output

All of the above tags can be enabled/disabled programatically at any time, and there are others that are not enabled by default. You can even add your own custom tag. See the display() method in "CONFIGURATION METHODS" for further details.



Builds and returns a new Logging::Simple object. All arguments are optional, and they can all be set using accessor methods after instantiation. These params are:

    name        => $str  # optional, default is undef
    level       => $num  # default 4, options, 0..7, -1 to disable all
    file        => $str  # optional, default undef, send in a filename
    write_mode  => $str  # defaults to append, other option is 'write'
    print       => $bool # default on, enable/disable output and return instead
    display     => $bool # default on, enable/disable log message tags


Returns the name of the log, if available. Send in a string to set it.


Set and return the facility level. Will return the current value with a param sent in or not. It can be changed at any time. Note that you can set this with the LS_LEVEL environment variable, at any time. the next method call regardless of what it is will set it appropriately.

You can also send in -1 as a level to disable all levels, or send in the level prepended with a = to log *only* that level (eg: $log->level('=3').

file('file.log', 'mode')

By default, we write to STDOUT. Send in the name of a file to write there instead. Mode is optional; we'll append to the file by default. Send in 'w' or 'write' to overwrite the file.


List of log entry tags, and default printing status:

    name  => 1, # specified in new() or name()
    time  => 1, # timestamp
    label => 1, # the string value of the level being called
    pid   => 0, # process ID
    proc  => 0, # "filename|line number" of the caller

In hash param mode, send in any or all of the tags with 1 (enable) or 0 (disable).

You can also send in 1 to enable all of the tags, or 0 to disable them all.


Send in an array reference of eight custom labels. We will map them in order to the levels 0 through 7, and your labels will be displayed in the log entries.

Send in 0 to disable your custom labels.


This will create a custom tag in your output, and place it at the first column of the output. Send in 0 (false) to disable/clear it.


Default is enabled. If disabled, we won't print at all, and instead, return the log entry as a scalar string value.


This method will create a clone of the existing Logging::Simple object, and then concatenate the parent's name with the optional name sent in here for easy identification in the logs.

All settings employed by the parent will be used in the child, unless explicity changed via the methods.

In a module or project, you can create a top-level log object, then in all subs, create a child with the sub's name to easily identify flow within the log. In an OO project, stuff the parent log into the main object, and clone it from there.



All log facilities are called by their corresponing numbered sub, eg:

    $log->_0("level 0 entry");
    $log->_7("level 7 entry");


Log the message, along with the trace confess() produces, and croak's immediately.


These methods may be handy to the end user, but aren't required for end-use.


Returns the hash of level_num => level_name mapping.

If the optional integer $level is sent in, we'll return the level_name of the level.


Returns the current time in the following format: 2016-03-17 17:51:02.241


Steve Bertrand, <steveb at>


Please report any bugs or feature requests to



CPAN Testers:


You can find documentation for this module with the perldoc command.

    perldoc Logging::Simple


There are too many other logging modules to list here, but the idea for this one came from Log::Basic. However, this one was written completely from scratch.


Copyright 2016 Steve Bertrand.

This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.

See for more information.