NAME
Log::ger::Manual::FAQ - FAQ on Log::ger
VERSION
version 0.015
GENERAL
How to use OO style?
The default in Log::ger is to use procedural style:
use Log::ger;
log_warn("blah");
if (log_is_debug()) {
log_debug("Format: %s %s", "blah ...", {data=>'structure'});
}However, you can also use objects:
use Log::ger (); # don't initialize and export logger subroutines
my $log = Log::ger->get_logger;
$log->warn("blah");
if ($log->is_debug) {
$log->debug("Format: %s %s", "blah ...", {data=>'structure'});
}How to create multiple loggers?
For example, in Log::Any:
my $log = Log::Any->get_logger;
my $log_dump = Log::Any->get_logger(category => "dump"); # to dump contents
$log->debugf("Headers is: %s", $http_res->{headers});
$log_dump->debug($http_res->{content});in Log::ger:
# instead of installing to package, we setup objects (or hashes) for the
# secondary loggers
my $log_dump = Log::ger->get_logger(category => "dump");
log_debug("Headers is: %s", $http_res->{headers});
$log_dump->debug($http_res->{content});OUTPUT
How to send logs to several outputs?
Use Log::ger::Output::Composite, which can log to multiple outputs as well as multiple output of the same type (e.g. two or more File's).
How to send trace/debug messages to screen, but warnings/errors to file?
Using Log::ger::Output::Composite's per-output level:
Log::ger::Output Composite => (
Screen => {
level => ['trace', 'debug'],
},
File => {
conf => { path=>'/path/to/file.log' },
level => ['warn', 'error'],
},
);How to send trace/debug messages to a file, but warnings/errors to another file?
Using Log::ger::Output::Composite's per-output level:
Log::ger::Output Composite => (
File => [
{
conf => { path=>'file1.log' },
level => ['trace', 'debug'],
},
{
conf => { path=>'file2.log' },
level => ['warn', 'error'],
},
],
);How to filter by category?
Using Log::ger::Output::Composite.
TODO example.
How to log warnings/die messages?
TODO
LEVEL
How to use custom levels?
One way:
use Log::ger ();
BEGIN {
our %Log::ger::Levels = (
critical => 1,
error => 2,
warning => 3,
info => 4,
extra => 5,
);
our %Log::ger::Level_Aliases = (
warn => 3,
verbose => 4,
);Do this before initializing any package with use Log::ger. The above example will create these logging routines: log_critical, log_error, log_warning, log_info, log_extra. The aliases won't get the logging routines but Log::ger::Util::numeric_level will recognize them.
FORMAT & LAYOUT
How to do sprintf-style formatting?
By default, the Log::ger formatter already does sprintf-style formatting:
log_warn("Format %s %s", "blah ...", {data=>'structure'});If there is only one argument, no formatting is done.
log_warn("blah ...");Why doesn't Log::ger log multiple arguments?
Logging multiple arguments is not supported by the default formatter because by default Log::ger adopts sprintf style:
log_warn("blah ...", "more blah ...");Either join the arguments first, use sprintf style, or use some of the other formatters that support this, e.g. Log::ger::Like::LogAny.
How to use deferred calculation of arguments?
Use a formatter like Log::ger::Format::Block, or Log::ger::Format::Flogger, or develop your own formatter to do what you want.
You can also do this:
if (log_is_trace()) {
log_trace("Format %s", $foo->something_that_is_expensive_to_calculate);
}How to dump data structures?
The default formatter already dumps data structures:
log_warn("Format %s %s", "blah ...", {data=>'structure'});How to log raw data structure?
You can use a formatter like Log::ger::Format::None which will prevent your log message from being stringified. To output this to destination, combine this with a layout plugin like Log::ger::Layout::JSON or Log::ger::Layout::LTSV. Or perhaps write your own output module that accepts raw data structure instead of formatted string and send it somewhere.
How to do custom formatting?
For example, a la Log::Contextual:
log_warn { 'The number of stuffs is: ' . $obj->stuffs_count };See Log::ger::Format::Block for an example.
How to add timestamps?
Use a layouter, e.g. Log::ger::Layout::Pattern.
How to use microsecond in timestamps?
TODO
How to redact sensitive information?
TODO
TARGETS
How to customize format/layout, output, plugin on a per-target basis?
To use a plugin only for the current package:
package MyPackage;
use Log::ger::Plugin;
Log::ger::Plugin->set_for_current_package(
'PluginName',
conf1 => ..., ...);
use Log::ger;Do the same thing for format (using Log::ger::Format), layout (using Log::ger::Layout), or output (using Log::ger::Output).
SEE ALSO
AUTHOR
perlancar <perlancar@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 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.