Log::Dispatch::Output - Base class for all Log::Dispatch::* objects


version 2.71


  package Log::Dispatch::MySubclass;

  use Log::Dispatch::Output;
  use base qw( Log::Dispatch::Output );

  sub new {
      my $proto = shift;
      my $class = ref $proto || $proto;

      my %p = @_;

      my $self = bless {}, $class;


      # Do more if you like

      return $self;

  sub log_message {
      my $self = shift;
      my %p    = @_;

      # Do something with message in $p{message}



This module is the base class from which all Log::Dispatch::* objects should be derived.


The constructor, new, must be overridden in a subclass. See Output Classes for a description of the common parameters accepted by this constructor.


This class provides the following methods:


This should be called from a subclass's constructor. Make sure to pass the arguments in @_ to it. It sets the object's name and minimum level from the passed parameters It also sets up two other attributes which are used by other Log::Dispatch::Output methods, level_names and level_numbers. Subclasses will perform parameter validation in this method, and must also call the superclass's method.


Returns the object's name.


Returns the object's minimum log level.


Returns the object's maximum log level.


Returns a list of the object's accepted levels (by name) from minimum to maximum.

$output->log( level => $, message => $ )

Sends a message if the level is greater than or equal to the object's minimum level. This method applies any message formatting callbacks that the object may have.

$output->_should_log ($)

This method is called from the log() method with the log level of the message to be logged as an argument. It returns a boolean value indicating whether or not the message should be logged by this particular object. The log() method will not process the message if the return value is false.

$output->_level_as_number ($)

This method will take a log level as a string (or a number) and return the number of that log level. If not given an argument, it returns the calling object's log level instead. If it cannot determine the level then it will croak.

$output->add_callback( $code )

Adds a callback (like those given during construction). It is added to the end of the list of callbacks.

$dispatch->remove_callback( $code )

Remove the given callback from the list of callbacks.


This class should be used as the base class for all logging objects you create that you would like to work under the Log::Dispatch architecture. Subclassing is fairly trivial. For most subclasses, if you simply copy the code in the SYNOPSIS and then put some functionality into the log_message method then you should be all set. Please make sure to use the _basic_init method as described above.

The actual logging implementation should be done in a log_message method that you write. Do not override log!.


Bugs may be submitted at


The source code repository for Log-Dispatch can be found at


Dave Rolsky <>


This software is Copyright (c) 2023 by Dave Rolsky.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)

The full text of the license can be found in the LICENSE file included with this distribution.