/ 
Log-Dispatch-Config-0.04
River stage two • 12 direct dependents • 21 total dependents
/ Log::Dispatch::Config

NAME

Log::Dispatch::Config - Log4j for Perl

SYNOPSIS

use Log::Dispatch::Config;
Log::Dispatch::Config->configure('/path/to/config');

my $dispatcher = Log::Dispatch::Config->instance;

# or the same (may be deprecated)
my $dispatcher = Log::Dispatch->instance;

DESCRIPTION

Log::Dispatch::Config is a subclass of Log::Dispatch and provides a way to configure Log::Dispatch object with configulation file (in AppConfig format). I mean, this is log4j for Perl, not with all API compatibility though.

METHOD

This module has a class method configure which parses config file for later creation of the Log::Dispatch::Config singleton instance. (Actual construction of the object is done in the first instance call).

So, what you should do is call configure method once in somewhere (like startup.pl in mod_perl), then you can get configured dispatcher instance via Log::Dispatch::Config->instance.

Formerly, configure method declares instance method in Log::Dispatch namespace. Now it inherits from Log::Dispatch, so the namespace pollution is not necessary. Currrent version still defines one-liner shortcut:

sub Log::Dispatch::instance { Log::Dispatch::Config->instance }

so still you can call Log::Dispatch->instance, if you prefer, or for backward compatibility.

CONFIGURATION

Here is an example of the config file:

dispatchers = file screen

file.class = Log::Dispatch::File
file.min_level = debug
file.filename = /path/to/log
file.mode = append
file.format = [%d] [%p] %m at %F line %L%n

screen.class = Log::Dispatch::Screen
screen.min_level = info
screen.stderr = 1
screen.format = %m

Config file is parsed with AppConfig module, see AppConfig when you face configuration parsing error.

GLOBAL PARAMETERS

dispatchers
dispatchers = file screen

dispatchers defines logger names, which will be splitted by spaces. If this parameter is unset, no logging is done.

format
format = [%d] [%p] %m at %F line %L%n
format = [${datetime}] [${prioity}] ${message} at ${filename} line ${line}\n

format defines log format. %X style and ${XXX} style are both supported. Possible conversions format are

%d ${datetime}	datetime string
%p ${priority}	priority (debug, info, warning ...)
%m ${message}		message string
%F ${filename}	filename
%L ${line}		line number
%P ${package}		package
%n 			newline (\n)

format defined here would apply to all the log messages to dispatchers. This parameter is optional.

PARAMETERS FOR EACH DISPATCHER

Parameters for each dispatcher should be prefixed with "name.", where "name" is the name of each one, defined in global dispatchers parameter.

class
screen.class = Log::Dispatch::Screen

class defines class name of Log::Dispatch subclasses. This parameter is essential.

format
screen.format = -- %m --

format defines log format which would be applied only to the dispatcher. Note that if you define global format also, %m is double formated (first global one, next each dispatcher one). This parameter is optional.

(others)
screen.min_level = info
screen.stderr = 1

Other parameters would be passed to the each dispatcher construction. See Log::Dispatch::* manpage for the details.

SINGLETON

Declared instance method would make Log::Dispatch::Config class singleton, so multiple calls of instance will all result in returning same object.

my $one = Log::Dispatch::Config->instance;
my $two = Log::Dispatch::Config->instance; # same as $one

See GoF Design Pattern book for Singleton Pattern.

But in practice, in persistent environment like mod_perl, Singleton instance is not so useful. Log::Dispatch::Config defines instance method so that the object reloads itself when configuration file is modified since its last object creation time.

TODO

  • LogLevel configuration depending on caller package like log4j?

AUTHOR

Tatsuhiko Miyagawa <miyagawa@bulknews.net>

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

SEE ALSO

Log::Dispatch, AppConfig