NAME¶
Log::Dispatch - Dispatches messages to one or more outputs
VERSION¶
version 2.44
SYNOPSIS¶
use Log::Dispatch;
# Simple API
#
my $log = Log::Dispatch->new(
outputs => [
[ 'File', min_level => 'debug', filename => 'logfile' ],
[ 'Screen', min_level => 'warning' ],
],
);
$log->info('Blah, blah');
# More verbose API
#
my $log = Log::Dispatch->new();
$log->add(
Log::Dispatch::File->new(
name => 'file1',
min_level => 'debug',
filename => 'logfile'
)
);
$log->add(
Log::Dispatch::Screen->new(
name => 'screen',
min_level => 'warning',
)
);
$log->log( level => 'info', message => 'Blah, blah' );
my $sub = sub { my %p = @_; return reverse $p{message}; };
my $reversing_dispatcher = Log::Dispatch->new( callbacks => $sub );
DESCRIPTION¶
This module manages a set of Log::Dispatch::* output objects that can be logged
to via a unified interface.
The idea is that you create a Log::Dispatch object and then add various logging
objects to it (such as a file logger or screen logger). Then you call the
"log" method of the dispatch object, which passes the message to
each of the objects, which in turn decide whether or not to accept the message
and what to do with it.
This makes it possible to call single method and send a message to a log file,
via email, to the screen, and anywhere else, all with very little code needed
on your part, once the dispatching object has been created.
METHODS¶
This class provides the following methods:
Log::Dispatch->new(...)¶
This method takes the following parameters:
- •
- outputs( [ [ class, params, ... ], [ class, params, ... ], ... ] )
This parameter is a reference to a list of lists. Each inner list consists
of a class name and a set of constructor params. The class is
automatically prefixed with 'Log::Dispatch::' unless it begins with '+',
in which case the string following '+' is taken to be a full classname.
e.g.
outputs => [ [ 'File', min_level => 'debug', filename => 'logfile' ],
[ '+My::Dispatch', min_level => 'info' ] ]
For each inner list, a new output object is created and added to the
dispatcher (via the "add()" method).
See "OUTPUT CLASSES" for the parameters that can be used when
creating an output object.
- •
- callbacks( \& or [ \&, \&, ... ] )
This parameter may be a single subroutine reference or an array reference of
subroutine references. These callbacks will be called in the order they
are given and passed a hash containing the following keys:
( message => $log_message, level => $log_level )
In addition, any key/value pairs passed to a logging method will be passed
onto your callback.
The callbacks are expected to modify the message and then return a single
scalar containing that modified message. These callbacks will be called
when either the "log" or "log_to" methods are called
and will only be applied to a given message once. If they do not return
the message then you will get no output. Make sure to return the
message!
$dispatch->clone()¶
This returns a
shallow clone of the original object. The underlying
output objects and callbacks are shared between the two objects. However any
changes made to the outputs or callbacks that the object contains are not
shared.
$dispatch->log( level => $, message => $ or \& )¶
Sends the message (at the appropriate level) to all the output objects that the
dispatcher contains (by calling the "log_to" method repeatedly).
This method also accepts a subroutine reference as the message argument. This
reference will be called only if there is an output that will accept a message
of the specified level.
$dispatch->debug (message), info (message), ...¶
You may call any valid log level (including valid abbreviations) as a method
with a single argument that is the message to be logged. This is converted
into a call to the "log" method with the appropriate level.
For example:
$log->alert('Strange data in incoming request');
translates to:
$log->log( level => 'alert', message => 'Strange data in incoming request' );
If you pass an array to these methods, it will be stringified as is:
my @array = ('Something', 'bad', 'is', 'here');
$log->alert(@array);
# is equivalent to
$log->alert("@array");
You can also pass a subroutine reference, just like passing one to the
"log()" method.
$dispatch->log_and_die( level => $, message => $ or \& )¶
Has the same behavior as calling "log()" but calls
"_die_with_message()" at the end.
$dispatch->log_and_croak( level => $, message => $ or \& )¶
This method adjusts the $Carp::CarpLevel scalar so that the croak comes from the
context in which it is called.
You can throw exception objects by subclassing this method.
If the "carp_level" parameter is present its value will be added to
the current value of $Carp::CarpLevel.
$dispatch->log_to( name => $, level => $, message => $ )¶
Sends the message only to the named object. Note: this will not properly handle
a subroutine reference as the message.
$dispatch->add_callback( $code )¶
Adds a callback (like those given during construction). It is added to the end
of the list of callbacks. Note that this can also be called on individual
output objects.
$dispatch->callbacks()¶
Returns a list of the callbacks in a given output.
$dispatch->level_is_valid( $string )¶
Returns true or false to indicate whether or not the given string is a valid log
level. Can be called as either a class or object method.
$dispatch->would_log( $string )¶
Given a log level, returns true or false to indicate whether or not anything
would be logged for that log level.
$dispatch->is_$level¶
There are methods for every log level: "is_debug()",
"is_warning()", etc.
This returns true if the logger will log a message at the given level.
$dispatch->add( Log::Dispatch::* OBJECT )¶
Adds a new output object to the dispatcher. If an object of the same name
already exists, then that object is replaced, with a warning if $^W is true.
$dispatch->remove($)¶
Removes the object that matches the name given to the remove method. The return
value is the object being removed or undef if no object matched this.
$dispatch->outputs()¶
Returns a list of output objects.
$dispatch->output( $name )¶
Returns the output object of the given name. Returns undef or an empty list,
depending on context, if the given output does not exist.
$dispatch->_die_with_message( message => $, carp_level => $ )¶
This method is used by "log_and_die" and will either
die() or
croak() depending on the value of "message": if it's a
reference or it ends with a new line then a plain die will be used, otherwise
it will croak.
OUTPUT CLASSES¶
An output class - e.g. Log::Dispatch::File or Log::Dispatch::Screen - implements
a particular way of dispatching logs. Many output classes come with this
distribution, and others are available separately on CPAN.
The following common parameters can be used when creating an output class. All
are optional. Most output classes will have additional parameters beyond
these, see their documentation for details.
- •
- name ($)
A name for the object (not the filename!). This is useful if you want to
refer to the object later, e.g. to log specifically to it or remove it.
By default a unique name will be generated. You should not depend on the
form of generated names, as they may change.
- •
- min_level ($)
The minimum logging level this object will accept. Required.
- •
- max_level ($)
The maximum logging level this object will accept. By default the maximum is
the highest possible level (which means functionally that the object has
no maximum).
- •
- callbacks( \& or [ \&, \&, ... ] )
This parameter may be a single subroutine reference or an array reference of
subroutine references. These callbacks will be called in the order they
are given and passed a hash containing the following keys:
( message => $log_message, level => $log_level )
The callbacks are expected to modify the message and then return a single
scalar containing that modified message. These callbacks will be called
when either the "log" or "log_to" methods are called
and will only be applied to a given message once. If they do not return
the message then you will get no output. Make sure to return the
message!
- •
- newline (0|1)
If true, a callback will be added to the end of the callbacks list that adds
a newline to the end of each message. Default is false, but some output
classes may decide to make the default true.
LOG LEVELS¶
The log levels that Log::Dispatch uses are taken directly from the syslog man
pages (except that I expanded them to full words). Valid levels are:
- debug
- info
- notice
- warning
- error
- critical
- alert
- emergency
Alternately, the numbers 0 through 7 may be used (debug is 0 and emergency is
7). The syslog standard of 'err', 'crit', and 'emerg' is also acceptable. We
also allow 'warn' as a synonym for 'warning'.
SUBCLASSING¶
This module was designed to be easy to subclass. If you want to handle messaging
in a way not implemented in this package, you should be able to add this with
minimal effort. It is generally as simple as subclassing Log::Dispatch::Output
and overriding the "new" and "log_message" methods. See
the Log::Dispatch::Output docs for more details.
If you would like to create your own subclass for sending email then it is even
simpler. Simply subclass Log::Dispatch::Email and override the
"send_email" method. See the Log::Dispatch::Email docs for more
details.
The logging levels that Log::Dispatch uses are borrowed from the standard UNIX
syslog levels, except that where syslog uses partial words ("err")
Log::Dispatch also allows the use of the full word as well
("error").
Log::Dispatch::DBI¶
Written by Tatsuhiko Miyagawa. Log output to a database table.
Log::Dispatch::FileRotate¶
Written by Mark Pfeiffer. Rotates log files periodically as part of its usage.
Log::Dispatch::File::Stamped¶
Written by Eric Cholet. Stamps log files with date and time information.
Log::Dispatch::Jabber¶
Written by Aaron Straup Cope. Logs messages via Jabber.
Log::Dispatch::Tk¶
Written by Dominique Dumont. Logs messages to a Tk window.
Log::Dispatch::Win32EventLog¶
Written by Arthur Bergman. Logs messages to the Windows event log.
Log::Log4perl¶
An implementation of Java's log4j API in Perl. Log messages can be limited by
fine-grained controls, and if they end up being logged, both native Log4perl
and Log::Dispatch appenders can be used to perform the actual logging job.
Created by Mike Schilli and Kevin Goess.
Log::Dispatch::Config¶
Written by Tatsuhiko Miyagawa. Allows configuration of logging via a text file
similar (or so I'm told) to how it is done with log4j. Simpler than
Log::Log4perl.
Log::Agent¶
A very different API for doing many of the same things that Log::Dispatch does.
Originally written by Raphael Manfredi.
SUPPORT¶
Please submit bugs and patches to the CPAN RT system at
http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Log%3A%3ADispatch or via email
at bug-log-dispatch@rt.cpan.org.
Support questions can be sent to me at my email address, shown below.
DONATIONS¶
If you'd like to thank me for the work I've done on this module, please consider
making a "donation" to me via PayPal. I spend a lot of free time
creating free software, and would appreciate any support you'd care to offer.
Please note that
I am not suggesting that you must do this in order for
me to continue working on this particular software. I will continue to do so,
inasmuch as I have in the past, for as long as it interests me.
Similarly, a donation made in this way will probably not make me work on this
software much more, unless I get so many donations that I can consider working
on free software full time, which seems unlikely at best.
To donate, log into PayPal and send money to autarch@urth.org or use the button
on this page: <
http://www.urth.org/~autarch/fs-donation.html>
SEE ALSO¶
Log::Dispatch::ApacheLog, Log::Dispatch::Email, Log::Dispatch::Email::MailSend,
Log::Dispatch::Email::MailSender, Log::Dispatch::Email::MailSendmail,
Log::Dispatch::Email::MIMELite, Log::Dispatch::File,
Log::Dispatch::File::Locked, Log::Dispatch::Handle, Log::Dispatch::Output,
Log::Dispatch::Screen, Log::Dispatch::Syslog
AUTHOR¶
Dave Rolsky <autarch@urth.org>
COPYRIGHT AND LICENSE¶
This software is Copyright (c) 2014 by Dave Rolsky.
This is free software, licensed under:
The Artistic License 2.0 (GPL Compatible)