NAME
    CGI::Application::Plugin::LogDispatch - Add Log::Dispatch support to
    CGI::Application

SYNOPSIS
     package My::App;

     use CGI::Application::Plugin::LogDispatch;

     sub cgiapp_init {
       my $self = shift;

       # calling log_config is optional as
       # some simple defaults will be used
       $self->log_config(
         LOG_DISPATCH_MODULES => [ 
           {    module => 'Log::Dispatch::File',
                  name => 'debug',
              filename => '/tmp/debug.log',
             min_level => 'debug',
           },
         ]
       );
     }

     sub myrunmode {
       my $self = shift;

       $self->log->info('Information message');
       $self->log->debug('Debug message');
     }

     - or as a class based singleton -

     package My::App;

     use CGI::Application::Plugin::LogDispatch (
       LOG_DISPATCH_MODULES => [ 
         {    module => 'Log::Dispatch::File',
                name => 'debug',
            filename => '/tmp/debug.log',
           min_level => 'debug',
         },
       ]
     );

     My::App->log->info('Information message');

     sub myrunmode {
       my $self = shift;

       $self->log->info('This also works');
     }

DESCRIPTION
    CGI::Application::Plugin::LogDispatch adds logging support to your
    CGI::Application modules by providing a Log::Dispatch dispatcher object
    that is accessible from anywhere in the application.

METHODS
  log
    This method will return the current Log::Dispatch dispatcher object. The
    Log::Dispatch object is created on the first call to this method, and
    any subsequent calls will return the same object. This effectively
    creates a singleton log dispatcher for the duration of the request. If
    "log_config" has not been called before the first call to "log", then it
    will choose some sane defaults to create the dispatcher object (the
    exact default values are defined below).

      # retrieve the log object
      my $log = $self->log;
      $log->warning("something's not right!";
      $log->emergency("It's all gone pear shaped!";
 
      - or -
 
      # use the log object directly
      $self->log->debug(Data::Dumper::Dumper(\%hash));

      - or - 

      # if you configured it as a singleton
      My::App->log->debug('This works too');

  log_config
    This method can be used to customize the functionality of the
    CGI::Application::Plugin::LogDispatch module. Calling this method does
    not mean that a new Log::Dispatch object will be immediately created.
    The log object will not be created until the first call to $self->log.

    The recommended place to call "log_config" is in the "cgiapp_init" stage
    of CGI::Application. If this method is called after the log object has
    already been accessed, then it will die with an error message.

    If this method is not called at all then a reasonable set of defaults
    will be used (the exact default values are defined below).

    The following parameters are accepted:

    LOG_DISPATCH_OPTIONS
        This allows you to customize how the Log::Dispatch object is created
        by providing a hash of options that will be passed to the
        Log::Dispatch constructor. Please see the documentation for
        Log::Dispatch for the exact syntax of the parameters. Surprisingly
        enough you will usually not need to use this option, instead look at
        the LOG_DISPATCH_MODULES option.

         LOG_DISPATCH_OPTIONS => {
              callbacks => sub { my %h = @_; return time().': '.$h{message}; },
         }

    LOG_DISPATCH_MODULES
        This option allows you to specify the Log::Dispatch::* modules that
        you wish to use to log messages. You can list multiple dispatch
        modules, each with their own set of options. Format the options in
        an array of hashes, where each hash contains the options for the
        Log::Dispatch:: module you are configuring and also include a
        'module' parameter containing the name of the dispatch module. See
        below for an example. You can also add an 'append_newline' option to
        automatically append a newline to each log entry for this dispatch
        module (this option is not needed if you already specified the
        APPEND_NEWLINE option listed below which will add a newline for all
        dispatch modules).

         LOG_DISPATCH_MODULES => [ 
           {         module => 'Log::Dispatch::File',
                       name => 'messages',
                   filename => '/tmp/messages.log',
                  min_level => 'info',
             append_newline => 1
           },
           {         module => 'Log::Dispatch::Email::MailSend',
                       name => 'email',
                         to => [ qw(foo@bar.com bar@baz.org ) ],
                     subject => 'Oh No!!!!!!!!!!',
                  min_level => 'emerg'
           }
         ]

    APPEND_NEWLINE
        By default Log::Dispatch does not append a newline to the end of the
        log messages. By setting this option to a true value, a newline
        character will automatically be added to the end of the log message.

         APPEND_NEWLINE => 1

    LOG_METHOD_EXECUTION (EXPERIMENTAL)
        This option will allow you to log the execution path of your
        program. Set LOG_METHOD_EXECUTION to a list of all the modules you
        want to be logged. This will automatically send a debug message at
        the start and end of each method/function that is called in the
        modules you listed. The parameters passed, and the return value will
        also be logged. This can be useful by tracing the program flow in
        the logfile without having to resort to the debugger.

         LOG_METHOD_EXECUTION => [qw(__PACKAGE__ CGI::Application CGI)],

        WARNING: This hasn't been heavily tested, although it seems to work
        fine for me. Also, a closure is created around the log object, so
        some care may need to be taken when using this in a persistent
        environment like mod_perl. This feature depends on the
        Sub::WrapPackages module.

  DEFAULT OPTIONS
    The following example shows what options are set by default (ie this is
    what you would get if you do not call log_config). A single
    Log::Dispatch::Screen module that writes error messages to STDERR with a
    minimum log level of debug.

     $self->log_config(
       LOG_DISPATCH_MODULES => [ 
         {        module => 'Log::Dispatch::Screen',
                    name => 'screen',
                  stderr => 1,
               min_level => 'debug',
          append_newline => 1
         }
       ],
     );

    Here is a more customized example that uses two file appenders, and an
    email gateway. Here all debug messages are sent to /tmp/debug.log, and
    all messages above are sent to /tmp/messages.log. Also, any emergency
    messages are emailed to foo@bar.com and bar@baz.org.

     $self->log_config(
       LOG_DISPATCH_MODULES => [ 
         {    module => 'Log::Dispatch::File',
                name => 'debug',
            filename => '/tmp/debug.log',
           min_level => 'debug',
           max_level => 'debug'
         },
         {    module => 'Log::Dispatch::File',
                name => 'messages',
            filename => '/tmp/messages.log',
           min_level => 'info'
         },
         {    module => 'Log::Dispatch::Email::MailSend',
                name => 'email',
                  to => [ qw(foo@bar.com bar@baz.org ) ],
              subject => 'Oh No!!!!!!!!!!',
           min_level => 'emerg'
         }
       ],
       APPEND_NEWLINE => 1,
     );
 
EXAMPLE
    In a CGI::Application module:

      # configure the log modules once during the init stage
      sub cgiapp_init {
        my $self = shift;
 
        # Configure the session
        $self->log_config(
          LOG_DISPATCH_MODULES => [ 
            {    module => 'Log::Dispatch::File',
                   name => 'messages',
               filename => '/tmp/messages.log',
              min_level => 'error'
            },
            {    module => 'Log::Dispatch::Email::MailSend',
                   name => 'email',
                     to => [ qw(foo@bar.com bar@baz.org ) ],
                 subject => 'Oh No!!!!!!!!!!',
              min_level => 'emerg'
            }
          ],
          APPEND_NEWLINE => 1,
        );
 
      }
 
      sub cgiapp_prerun {
        my $self = shift;
 
        $self->log->debug("Current runmode:  ".$self->get_current_runmode);
      }
 
      sub my_runmode {
        my $self = shift;
        my $log  = shift;

        if ($ENV{'REMOTE_USER'}) {
          $log->info("user ".$ENV{'REMOTE_USER'});
        }

        # etc...
      }

SINGLETON SUPPORT
    This module can be used as a singleton object. This means that when the
    object is created, it will remain accessable for the duration of the
    process. This can be useful in persistent environments like mod_perl and
    PersistentPerl, since the object only has to be created one time, and
    will remain in memory across multiple requests. It can also be useful if
    you want to setup a DIE handler, or WARN handler, since you will not
    have access to the $self object.

    To use this module as a singleton you need to provide all configuration
    parameters as options to the use statement. The use statement will
    accept all the same parameters that the log_config method accepts, so
    see the documentation above for more details.

    When creating the singleton, the log object will be saved in the
    namespace of the module that created it. The singleton will also be
    inherited by any subclasses of this module.

    NOTE: Singleton support requires the Class::ISA module which is not
    installed automatically by this module.

SINGLETON EXAMPLE
      package My::App;
  
      use base qw(CGI::Application);
      use CGI::Application::Plugin::LogDispatch(
          LOG_DISPATCH_MODULES => [ 
            {    module => 'Log::Dispatch::File',
                   name => 'messages',
               filename => '/tmp/messages.log',
              min_level => 'error'
            },
          ],
          APPEND_NEWLINE => 1,
        );
 
      }
 
      sub cgiapp_prerun {
        my $self = shift;
 
        $self->log->debug("Current runmode:  ".$self->get_current_runmode);
      }
 
      sub my_runmode {
        my $self = shift;
        my $log  = shift;

        if ($ENV{'REMOTE_USER'}) {
          $log->info("user ".$ENV{'REMOTE_USER'});
        }

        # etc...
      }

      package My::App::Subclass;

      use base qw(My::App);

      # Setup a die handler that uses the logger
      $SIG{__DIE__} = sub { My::App::Subclass->log->emerg(@_); CORE::die(@_); };

      sub my_other_runmode {
        my $self = shift;

        $self->log->info("This will log to the logger configured in My::App");
      }

BUGS
    This is alpha software and as such, the features and interface are
    subject to change. So please check the Changes file when upgrading.

SEE ALSO
    CGI::Application, Log::Dispatch, Log::Dispatch::Screen,
    Sub::WrapPackages, perl(1)

AUTHOR
    Cees Hek <cees@crtconsulting.ca>

LICENSE
    Copyright (C) 2004 Cees Hek <cees@crtconsulting.ca>

    This library is free software. You can modify and or distribute it under
    the same terms as Perl itself.

