NAME

Log::ger::Manual::Tutorial::500_Category - Categories

VERSION

version 0.033.000

DESCRIPTION

WHAT ARE CATEGORIES?

Aside from filtering log messages by level, you can also filter by category. Category normally maps to Perl packages (but they can also be something else). For example:

 # in My/App/Module1.pm
 package My::App::Module1;
 use Log::ger;
 sub foo {
     log_warn("foo!");
 }
 1;

 # in My/App/Module2.pm
 package My::App::Module2;
 use Log::ger;
 sub bar {
     log_warn("bar!");
 }
 1;

Logger subroutines in My::App::Module1 will log messages under the category My::App::Module1, while logger subroutines in My::App::Module2 will log messages under the category My::App::Module2. In your application, you can do something like:

 use Log::ger::Output Composite => (
     outputs => { ... },
     category_level => {
         'My::App' => 'info',
         'My::App::Module1' => 'debug',
         'My::App::Module2' => 'error',
     },
 );

Categories work hierarchically. The above means, other modules under My::App, like My::App::Module3 or My::App::Module4::Submodule is set to level info.

LOGGING UNDER A DIFFERENT CATEGORY

 package My::App::Module4;
 use Log::ger ();
 my $log     = Log::ger->get_logger(); # by default will use the caller's package
 my $log_foo = Log::ger->get_logger(category => "Foo");

 $log->warn("This message will be logged under the category 'My::App::Module4'");
 $log_foo->warn("This message will be logged under the category 'Foo'");

PER-CATEGORY OUTPUT

To direct log messages under a certain category to its own output, for example category Foo to a separate file /path/foo.log while the rest go to /path/app.log, you can do something like this:

 use Log::ger::Output Composite => (
     outputs => {
         File => [
             {
                 conf => {path=>'/path/app.log'},
                 category_level => { Foo => 'off' },
             },
             {
                 conf => {path=>'/path/foo.log'},
                 level => 'off',
                 category_level => { Foo => 'trace' },
             },
         ],
     },
 );

So basically for /path/app.log you turn off the category Foo, while for /path/foo.log you turn off for all category except for Foo.

AUTHOR

perlancar <perlancar@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2020, 2019, 2018, 2017 by perlancar@cpan.org.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.