NAME

       Log::Contextual::Role::Router - Abstract interface between loggers and logging code blocks

SYNOPSIS

         package MyApp::Log::Router;

         use Moo;
         use Log::Contextual::SimpleLogger;

         with 'Log::Contextual::Role::Router';

         has logger => (is => 'lazy');

         sub _build_logger {
            return Log::Contextual::SimpleLogger->new({ levels_upto => 'debug' });
         }

         sub before_import {
            my ($self, %export_info) = @_;
            my $exporter = $export_info{exporter};
            my $target = $export_info{target};
            print STDERR "Package '$target' will import from '$exporter'\n";
         }

         sub after_import {
            my ($self, %export_info) = @_;
            my $exporter = $export_info{exporter};
            my $target = $export_info{target};
            print STDERR "Package '$target' has imported from '$exporter'\n";
         }

         sub handle_log_request {
            my ($self, %message_info) = @_;
            my $log_code_block = $message_info{message_sub};
            my $args = $message_info{message_args};
            my $log_level_name = $message_info{message_level};
            my $logger = $self->logger;
            my $is_active = $logger->can("is_${log_level_name}");

            return unless defined $is_active && $logger->$is_active;
            my $log_message = $log_code_block->(@$args);
            $logger->$log_level_name($log_message);
         }

         package MyApp::Log::Contextual;

         use Moo;
         use MyApp::Log::Router;

         extends 'Log::Contextual';

         #This example router is a singleton
         sub router {
            our $Router ||= MyApp::Log::Router->new
         }

         package main;

         use strict;
         use warnings;
         use MyApp::Log::Contextual qw(:log);

         log_info { "Hello there" };

DESCRIPTION

       Log::Contextual has three parts

       Export manager and logging method generator
           These tasks are handled by the "Log::Contextual" package.

       Logger selection and invocation
           The logging functions generated and exported by Log::Contextual call a method on an
           instance of a log router object which is responsible for invoking any loggers that
           should get an opportunity to receive the log message. The "Log::Contextual::Router"
           class implements the set_logger() and with_logger() functions as well as uses the arg_
           prefixed functions to configure itself and provide the standard "Log::Contextual"
           logger selection API.

       Log message formatting and output
           The logger objects themselves accept or reject a log message at a certain log level
           with a guard method per level. If the logger is going to accept the log message the
           router is then responsible for executing the log message code block and passing the
           generated message to the logging object's log method.

METHODS

       before_import($self, %import_info)
       after_import($self,  %import_info)
           These two required methods are called with identical arguments at two different places
           during the import process. The before_import() method is invoked prior to the logging
           subroutines being exported into the target package and after_import() is called when
           the export is completed but before control returns to the package that imported the
           API.

           The arguments are passed as a hash with the following keys:

           exporter
               This is the name of the package that has been imported. It can also be
               'Log::Contextual' itself. In the case of the synopsis the value for exporter would
               be 'MyApp::Log::Contextual'.

           target
               This is the package name that is importing the logging API. In the case of the
               synopsis the value would be 'main'.

           arguments
               This is a hash reference containing the configuration values that were provided
               for the import.  The key is the name of the configuration item that was specified
               without the leading hyphen ('-').  For instance if the logging API is imported as
               follows

                 use Log::Contextual qw( :log ), -logger => Custom::Logger->new({ levels => [qw( debug )] });

               then $import_info{arguments}->{logger} would contain that instance of
               Custom::Logger.

       handle_log_request($self, %message_info)
           This method is called by "Log::Contextual" when a log event happens. The arguments are
           passed as a hash with the following keys

           exporter
               This is the name of the package that created the logging methods used to generate
               the log event.

           caller_package
               This is the name of the package that the log event has happened inside of.

           caller_level
               This is an integer that contains the value to pass to caller() that will provide
               information about the location the log event was created at.

           log_level
               This is the name of the log level associated with the log event.

           message_sub
               This is the message generating code block associated with the log event passed as
               a subref. If the logger accepts the log request the router should execute the
               subref to create the log message and then pass the message as a string to the
               logger.

           message_args
               This is an array reference that contains the arguments given to the message
               generating code block.  When invoking the message generator it will almost
               certainly be expecting these argument values as well.

SEE ALSO

       "Log::Contextual"