log::nullloglite(3pm) [debian man page]

NullLogLite(3pm)					User Contributed Perl Documentation					  NullLogLite(3pm)

NAME

       Log::NullLogLite - The "Log::NullLogLite" class implements the Null Object pattern for the "Log::LogLite" class.

SYNOPSIS

	 use Log::NullLogLite;

	 # create new Log::NullLogLite object
	 my $log = new Log::NullLogLite();

	 ...

	 # we had an error (this entry will not be written to the log
	 # file because we use Log::NullLogLite object).
	 $log->write("Could not open the file ".$file_name.": $!", 4);

DESCRIPTION

       The "Log::NullLogLite" class is derived from the "Log::LogLite" class and implement the Null Object Pattern to let us to use the
       "Log::LogLite" class with null "Log::LogLite" objects.  We might want to do that if we use a "Log::LogLite" object in our code, and we do
       not want always to actually define a "Log::LogLite" object (i.e. not always we want to write to a log file). In such a case we will create
       a "Log::NullLogLite" object instead of the "Log::LogLite" object, and will use that object instead.  The object has all the methods that
       the "Log::LogLite" object has, but those methods do nothing. Thus our code will continue to run without any change, yet we will not have to
       define a log file path for the "Log::LogLite" object, and no log will be created.

CONSTRUCTOR

       new ( FILEPATH [,LEVEL [,DEFAULT_MESSAGE ]] )
	   The constructor. The parameters will not have any affect.  Returns the new Log::NullLogLite object.

METHODS

       write( MESSAGE [, LEVEL ] )
	   Does nothing. The parameters will not have any affect.  Returns nothing.

       level( [ LEVEL ] )
	   Does nothing. The parameters will not have any affect.  Returns -1.

       default_message( [ MESSAGE ] )
	   Does nothing. The parameters will not have any affect.  Returns empty string ("").

AUTHOR

       Rani Pinchuk, rani@cpan.org

COPYRIGHT

       Copyright (c) 2001-2002 Ockham Technology N.V. & Rani Pinchuk.  All rights reserved.  This package is free software; you can redistribute
       it and/or modify it under the same terms as Perl itself.

SEE ALSO

       Log::LogLite(3), The Null Object Pattern - Bobby Woolf - PLoP96 - published in Pattern Languages of Program Design 3
       (http://cseng.aw.com/book/0,,0201310112,00.html)

perl v5.10.0							    2009-05-13							  NullLogLite(3pm)

Log::Dispatch::Output(3)				User Contributed Perl Documentation				  Log::Dispatch::Output(3)

NAME

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

SYNOPSIS

	 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;

	     $self->_basic_init(%p);

	     # Do more if you like

	     return $self;
	 }

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

	     # Do something with message in $p{message}
	 }

	 1;

DESCRIPTION

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

CONSTRUCTOR

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

METHODS

       o   _basic_init(%p)

	   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.  It also sets up two other attributes which are used by other Log::Dispatch::Output methods, level_names and
	   level_numbers.

       o   name

	   Returns the object's name.

       o   min_level

	   Returns the object's minimum log level.

       o   max_level

	   Returns the object's maximum log level.

       o   accepted_levels

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

       o   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.

       o   _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.

       o   _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.

       o   add_callback( $code )

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

   Subclassing
       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 directed.

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

AUTHOR

       Dave Rolsky, <autarch@urth.org>

perl v5.12.1							    2009-09-22						  Log::Dispatch::Output(3)