Log/Dispatch/Config.pm

package Log::Dispatch::Config;

use strict;
use vars qw($VERSION);
$VERSION = 1.02;

use Log::Dispatch 2.00;
use base qw(Log::Dispatch);

# caller depth: can be changed from outside
$Log::Dispatch::Config::CallerDepth = 0;

sub _croak { require Carp; Carp::croak(@_); }

# accessor for symblic reference
sub __instance {
    my $class = shift;
    no strict 'refs';
    my $instance = "$class\::_instance";
    $$instance = shift if @_;
    return $$instance;
}

sub _configurator_for {
    my($class, $stuff) = @_;
    return $stuff if UNIVERSAL::isa($stuff, 'Log::Dispatch::Configurator');
    require Log::Dispatch::Configurator::AppConfig;
    return Log::Dispatch::Configurator::AppConfig->new($stuff);
}

sub configure {
    my($class, $stuff) = @_;
    _croak "no config file or configurator supplied" unless $stuff;
    my $config = $class->_configurator_for($stuff);
    $config->myinit;
    $class->__instance($config);
}

sub configure_and_watch {
    my $class = shift;
    $class->configure(@_);
    $class->__instance->should_watch(1); # tells conf to watch config file
}

# backward compatibility
sub Log::Dispatch::instance { __PACKAGE__->instance; }

sub instance {
    my $class = shift;

    my $instance = $class->__instance or _croak "configure not yet called.";
    if ($instance->isa('Log::Dispatch::Config')) {
        # reload singleton on the fly
        $class->reload if $instance->needs_reload;
    }
    else {
        # first time call: $_instance is L::D::Configurator::*
        $class->__instance($class->create_instance($instance));
    }
    return $class->__instance;
}

sub needs_reload {
    my $self = shift;
    return $self->{config}->should_watch && $self->{config}->needs_reload;
}

sub reload {
    my $proto = shift;
    my $class = ref $proto || $proto;
    my $instance = $class->__instance;
    $instance->{config}->reload;
    $class->__instance($class->create_instance($instance->{config}));
}

sub create_instance {
    my($class, $config) = @_;
    $config->{LDC_ctime} = time;        # creation time

    my $global = $config->get_attrs_global;
    my $callback = $class->format_to_cb($global->{format}, 0);
    my %dispatchers;
    foreach my $disp (@{$global->{dispatchers}}) {
        $dispatchers{$disp} = $class->config_dispatcher(
            $disp, $config->get_attrs($disp),
        );
    }
    my %args;
    $args{callbacks} = $callback if defined $callback;
    my $instance = $class->new(%args);

    for my $dispname (keys %dispatchers) {
        my $logclass = delete $dispatchers{$dispname}->{class};
        $instance->add(
            $logclass->new(
                name => $dispname,
                %{$dispatchers{$dispname}},
            ),
        );
    }

    $instance->{config} = $config;
    return $instance;
}

sub config_dispatcher {
    my($class, $disp, $var) = @_;

    my $dispclass = $var->{class} or _croak "class param missing for $disp";

    eval qq{require $dispclass};
    _croak $@ if $@ && $@ !~ /locate/;

    if (exists $var->{format}) {
        $var->{callbacks} = $class->format_to_cb(delete $var->{format}, 2);
    }
    return $var;
}

sub format_to_cb {
    my($class, $format, $stack) = @_;
    return undef unless defined $format;

    # caller() called only when necessary
    my $needs_caller = $format =~ /%[FLP]/;
    return sub {
        my %p = @_;
        $p{p} = delete $p{level};
        $p{m} = delete $p{message};
        $p{n} = "\n";
        $p{'%'} = '%';

        if ($needs_caller) {
            my $depth = 0;
            $depth++ while caller($depth) =~ /^Log::Dispatch/;
            $depth += $Log::Dispatch::Config::CallerDepth;
            @p{qw(P F L)} = caller($depth);
        }

        my $log = $format;
        $log =~ s{
            (%d(?:{(.*?)})?)|   # $1: datetime $2: datetime fmt
            (?:%([%pmFLPn]))    # $3: others
        }{
            if ($1 && $2) {
                _strftime($2);
            }
            elsif ($1) {
                scalar localtime;
            }
            elsif ($3) {
                $p{$3};
            }
        }egx;
        return $log;
    };
}

{
    use vars qw($HasTimePiece);
    BEGIN { eval { require Time::Piece; $HasTimePiece = 1 }; }

    sub _strftime {
        my $fmt = shift;
        if ($HasTimePiece) {
            return Time::Piece->new->strftime($fmt);
        } else {
            require POSIX;
            return POSIX::strftime($fmt, localtime);
        }
    }
}

1;
__END__

=head1 NAME

Log::Dispatch::Config - Log4j for Perl

=head1 SYNOPSIS

  use Log::Dispatch::Config;
  Log::Dispatch::Config->configure('/path/to/log.conf');

  my $dispatcher = Log::Dispatch::Config->instance;
  $dispatcher->debug('this is debug message');
  $dispatcher->emergency('something *bad* happened!');

  # automatic reloading conf file, when modified
  Log::Dispatch::Config->configure_and_watch('/path/to/log.conf');

  # or if you write your own config parser:
  use Log::Dispatch::Configurator::XMLSimple;

  my $config = Log::Dispatch::Configurator::XMLSimple->new('log.xml');
  Log::Dispatch::Config->configure($config);

=head1 DESCRIPTION

Log::Dispatch::Config is a subclass of Log::Dispatch and provides a
way to configure Log::Dispatch object with configulation file
(default, in AppConfig format). I mean, this is log4j for Perl, not
with all API compatibility though.

=head1 METHOD

This module has a class method C<configure> which parses config file
for later creation of the Log::Dispatch::Config singleton instance.
(Actual construction of the object is done in the first C<instance>
call).

So, what you should do is call C<configure> method once in somewhere
(like C<startup.pl> in mod_perl), then you can get configured
dispatcher instance via C<Log::Dispatch::Config-E<gt>instance>.

=head1 CONFIGURATION

Here is an example of the config file:

  dispatchers = file screen

  file.class = Log::Dispatch::File
  file.min_level = debug
  file.filename = /path/to/log
  file.mode = append
  file.format = [%d] [%p] %m at %F line %L%n

  screen.class = Log::Dispatch::Screen
  screen.min_level = info
  screen.stderr = 1
  screen.format = %m

In this example, config file is written in AppConfig format. See
L<Log::Dispatch::Configurator::AppConfig> for details.

See L</"PLUGGABLE CONFIGURATOR"> for other config parsing scheme.

=head2 GLOBAL PARAMETERS

=over 4

=item dispatchers

  dispatchers = file screen

C<dispatchers> defines logger names, which will be splitted by spaces.
If this parameter is unset, no logging is done.

=item format

  format = [%d] [%p] %m at %F line %L%n

C<format> defines log format. Possible conversions format are

  %d    datetime string (ctime(3))
  %p    priority (debug, info, warning ...)
  %m    message string
  %F    filename
  %L    line number
  %P    package
  %n    newline (\n)
  %%    % itself

Note that datetime (%d) format is configurable by passing C<strftime>
fmt in braket after %d. (I know it looks quite messy, but its
compatible with Java Log4j ;)

  format = [%d{%Y%m%d}] %m  # datetime is now strftime "%Y%m%d"

If you have Time::Piece, this module uses its C<strftime>
implementation, otherwise POSIX.

C<format> defined here would apply to all the log messages to
dispatchers. This parameter is B<optional>.

See L</"CALLER STACK"> for details about package, line number and
filename.

=back

=head2 PARAMETERS FOR EACH DISPATCHER

Parameters for each dispatcher should be prefixed with "name.", where
"name" is the name of each one, defined in global C<dispatchers>
parameter.

You can also use C<.ini> style grouping like:

  [foo]
  class = Log::Dispatch::File
  min_level = debug

See L<Log::Dispatch::Configurator::AppConfig> for details.

=over 4

=item class

  screen.class = Log::Dispatch::Screen

C<class> defines class name of Log::Dispatch subclasses. This
parameter is B<essential>.

=item format

  screen.format = -- %m --

C<format> defines log format which would be applied only to the
dispatcher. Note that if you define global C<format> also, C<%m> is
double formated (first global one, next each dispatcher one). This
parameter is B<optional>.

=item (others)

  screen.min_level = info
  screen.stderr = 1

Other parameters would be passed to the each dispatcher
construction. See Log::Dispatch::* manpage for the details.

=back

=head1 SINGLETON

Declared C<instance> method would make C<Log::Dispatch::Config> class
singleton, so multiple calls of C<instance> will all result in
returning same object.

  my $one = Log::Dispatch::Config->instance;
  my $two = Log::Dispatch::Config->instance; # same as $one

See GoF Design Pattern book for Singleton Pattern.

But in practice, in persistent environment like mod_perl, lifetime of
Singleton instance becomes sometimes messy. If you want to reload
singleton object manually, call C<reload> method.

  Log::Dispatch::Config->reload;

And, if you want to reload object on the fly, as you edit C<log.conf>
or something like that, what you should do is to call
C<configure_and_watch> method on Log::Dispatch::Config instead of
C<configure>. Then C<instance> call will check mtime of configuration
file, and compares it with instanciation time of singleton object. If
config file is newer than last instanciation, it will automatically
reload object.

=head1 NAMESPACE COLLISION

If you use Log::Dispatch::Config in multiple projects on the same perl
interpreter (like mod_perl), namespace collision would be a
problem. Bizzare thing will happen when you call
C<Log::Dispatch::Config-E<gt>configure> multiple times with differenct
argument.

In such cases, what you should do is to define your own logger class.

  package My::Logger;
  use Log::Dispatch::Config;
  use base qw(Log::Dispatch::Config);

Or make wrapper for it. See L<POE::Component::Logger> implementation
by Matt Sergeant.

=head1 PLUGGABLE CONFIGURATOR

If you pass filename to C<configure> method call, this module handles
the config file with AppConfig. You can change config parsing scheme
by passing another pluggable configurator object.

Here is a way to declare new configurator class. The example below is
hardwired version equivalent to the one above in L</"CONFIGURATION">.

=over 4

=item *

Inherit from Log::Dispatch::Configurator.

  package Log::Dispatch::Configurator::Hardwired;
  use base qw(Log::Dispatch::Configurator);

Declare your own C<new> constructor. Stub C<new> method is defined in
Configurator base class, but you want to put parsing method in your
own constructor. In this example, we just bless reference. Note that
your object should be blessed hash.

  sub new { bless {}, shift }

=item *

Implement two required object methods C<get_attrs_global> and
C<get_attrs>.

C<get_attrs_global> should return hash reference of global parameters.
C<dispatchers> should be an array reference of names of dispatchers.

  sub get_attrs_global {
      my $self = shift;
      return {
          format => undef,
          dispatchers => [ qw(file screen) ],
      };
  }

C<get_attrs> accepts name of a dispatcher and should return hash
reference of parameters associated with the dispatcher.

  sub get_attrs {
      my($self, $name) = @_;
      if ($name eq 'file') {
          return {
              class     => 'Log::Dispatch::File',
              min_level => 'debug',
              filename  => '/path/to/log',
              mode      => 'append',
              format  => '[%d] [%p] %m at %F line %L%n',
          };
      }
      elsif ($name eq 'screen') {
          return {
              class     => 'Log::Dispatch::Screen',
              min_level => 'info',
              stderr    => 1,
              format  => '%m',
          };
      }
      else {
          die "invalid dispatcher name: $name";
      }
  }

=item *

Implement optional C<needs_reload> and C<reload>
methods. C<needs_reload> should return boolean value if the object is
stale and needs reloading itself. This method will be triggered when
you configure logging object with C<configure_and_watch> method.

Stub config file mtime based C<needs_reload> method is declared in
Log::Dispatch::Configurator, so if your config class is based on
filesystem files, you do not need to reimplement this.

If you do not need I<singleton-ness> at all, always return true.

  sub needs_reload { 1 }

C<reload> method should redo parsing of the config file. Configurator
base class has a stub null C<reload> method, so you should better
override it.

See Log::Dispatch::Configurator::AppConfig source code for details.

=item *

That's all. Now you can plug your own configurator (Hardwired) into
Log::Dispatch::Config. What you should do is to pass configurator
object to C<configure> method call instead of config file name.

  use Log::Dispatch::Config;
  use Log::Dispatch::Configurator::Hardwired;

  my $config = Log::Dispatch::Configurator::Hardwired->new;
  Log::Dispatch::Config->configure($config);

=back

=head1 CALLER STACK

When you call logging method from your subroutines / methods, caller
stack would increase and thus you can't see where the log really comes
from.

  package Logger;
  my $Logger = Log::Dispatch::Config->instance;

  sub logit {
      my($class, $level, $msg) = @_;
      $Logger->$level($msg);
  }

  package main;
  Logger->logit('debug', 'foobar');

You can adjust package variable C<$Log::Dispatch::Config::CallerDepth>
to increase the caller stack depth. The default value is 0.

  sub logit {
      my($class, $level, $msg) = @_;
      local $Log::Dispatch::Config::CallerDepth = 1;
      $Logger->$level($msg);
  }

Note that your log caller's namespace should not match against
C</^Log::Dispatch/>, which makes this module confusing.

=head1 AUTHOR

Tatsuhiko Miyagawa E<lt>miyagawa@bulknews.netE<gt> with much help from
Matt Sergeant E<lt>matt@sergeant.orgE<gt>.

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.

=head1 SEE ALSO

L<Log::Dispatch::Configurator::AppConfig>, L<Log::Dispatch>,
L<AppConfig>, L<POE::Component::Logger>

=cut
1	package Log::Dispatch::Config;
2
3	use strict;
4	use vars qw($VERSION);
5	$VERSION = 1.02;
6
7	use Log::Dispatch 2.00;
8	use base qw(Log::Dispatch);
9
10	# caller depth: can be changed from outside
11	$Log::Dispatch::Config::CallerDepth = 0;
12
13	sub _croak { require Carp; Carp::croak(@_); }
14
15	# accessor for symblic reference
16	sub __instance {
17	my $class = shift;
18	no strict 'refs';
19	my $instance = "$class\::_instance";
20	$$instance = shift if @_;
21	return $$instance;
22	}
23
24	sub _configurator_for {
25	my($class, $stuff) = @_;
26	return $stuff if UNIVERSAL::isa($stuff, 'Log::Dispatch::Configurator');
27	require Log::Dispatch::Configurator::AppConfig;
28	return Log::Dispatch::Configurator::AppConfig->new($stuff);
29	}
30
31	sub configure {
32	my($class, $stuff) = @_;
33	_croak "no config file or configurator supplied" unless $stuff;
34	my $config = $class->_configurator_for($stuff);
35	$config->myinit;
36	$class->__instance($config);
37	}
38
39	sub configure_and_watch {
40	my $class = shift;
41	$class->configure(@_);
42	$class->__instance->should_watch(1); # tells conf to watch config file
43	}
44
45	# backward compatibility
46	sub Log::Dispatch::instance { __PACKAGE__->instance; }
47
48	sub instance {
49	my $class = shift;
50
51	my $instance = $class->__instance or _croak "configure not yet called.";
52	if ($instance->isa('Log::Dispatch::Config')) {
53	# reload singleton on the fly
54	$class->reload if $instance->needs_reload;
55	}
56	else {
57	# first time call: $_instance is L::D::Configurator::*
58	$class->__instance($class->create_instance($instance));
59	}
60	return $class->__instance;
61	}
62
63	sub needs_reload {
64	my $self = shift;
65	return $self->{config}->should_watch && $self->{config}->needs_reload;
66	}
67
68	sub reload {
69	my $proto = shift;
70	my $class = ref $proto \|\| $proto;
71	my $instance = $class->__instance;
72	$instance->{config}->reload;
73	$class->__instance($class->create_instance($instance->{config}));
74	}
75
76	sub create_instance {
77	my($class, $config) = @_;
78	$config->{LDC_ctime} = time; # creation time
79
80	my $global = $config->get_attrs_global;
81	my $callback = $class->format_to_cb($global->{format}, 0);
82	my %dispatchers;
83	foreach my $disp (@{$global->{dispatchers}}) {
84	$dispatchers{$disp} = $class->config_dispatcher(
85	$disp, $config->get_attrs($disp),
86	);
87	}
88	my %args;
89	$args{callbacks} = $callback if defined $callback;
90	my $instance = $class->new(%args);
91
92	for my $dispname (keys %dispatchers) {
93	my $logclass = delete $dispatchers{$dispname}->{class};
94	$instance->add(
95	$logclass->new(
96	name => $dispname,
97	%{$dispatchers{$dispname}},
98	),
99	);
100	}
101
102	$instance->{config} = $config;
103	return $instance;
104	}
105
106	sub config_dispatcher {
107	my($class, $disp, $var) = @_;
108
109	my $dispclass = $var->{class} or _croak "class param missing for $disp";
110
111	eval qq{require $dispclass};
112	_croak $@ if $@ && $@ !~ /locate/;
113
114	if (exists $var->{format}) {
115	$var->{callbacks} = $class->format_to_cb(delete $var->{format}, 2);
116	}
117	return $var;
118	}
119
120	sub format_to_cb {
121	my($class, $format, $stack) = @_;
122	return undef unless defined $format;
123
124	# caller() called only when necessary
125	my $needs_caller = $format =~ /%[FLP]/;
126	return sub {
127	my %p = @_;
128	$p{p} = delete $p{level};
129	$p{m} = delete $p{message};
130	$p{n} = "\n";
131	$p{'%'} = '%';
132
133	if ($needs_caller) {
134	my $depth = 0;
135	$depth++ while caller($depth) =~ /^Log::Dispatch/;
136	$depth += $Log::Dispatch::Config::CallerDepth;
137	@p{qw(P F L)} = caller($depth);
138	}
139
140	my $log = $format;
141	$log =~ s{
142	(%d(?:{(.*?)})?)\| # $1: datetime $2: datetime fmt
143	(?:%([%pmFLPn])) # $3: others
144	}{
145	if ($1 && $2) {
146	_strftime($2);
147	}
148	elsif ($1) {
149	scalar localtime;
150	}
151	elsif ($3) {
152	$p{$3};
153	}
154	}egx;
155	return $log;
156	};
157	}
158
159	{
160	use vars qw($HasTimePiece);
161	BEGIN { eval { require Time::Piece; $HasTimePiece = 1 }; }
162
163	sub _strftime {
164	my $fmt = shift;
165	if ($HasTimePiece) {
166	return Time::Piece->new->strftime($fmt);
167	} else {
168	require POSIX;
169	return POSIX::strftime($fmt, localtime);
170	}
171	}
172	}
173
174	1;
175	__END__
176
177	=head1 NAME
178
179	Log::Dispatch::Config - Log4j for Perl
180
181	=head1 SYNOPSIS
182
183	use Log::Dispatch::Config;
184	Log::Dispatch::Config->configure('/path/to/log.conf');
185
186	my $dispatcher = Log::Dispatch::Config->instance;
187	$dispatcher->debug('this is debug message');
188	$dispatcher->emergency('something bad happened!');
189
190	# automatic reloading conf file, when modified
191	Log::Dispatch::Config->configure_and_watch('/path/to/log.conf');
192
193	# or if you write your own config parser:
194	use Log::Dispatch::Configurator::XMLSimple;
195
196	my $config = Log::Dispatch::Configurator::XMLSimple->new('log.xml');
197	Log::Dispatch::Config->configure($config);
198
199	=head1 DESCRIPTION
200
201	Log::Dispatch::Config is a subclass of Log::Dispatch and provides a
202	way to configure Log::Dispatch object with configulation file
203	(default, in AppConfig format). I mean, this is log4j for Perl, not
204	with all API compatibility though.
205
206	=head1 METHOD
207
208	This module has a class method C<configure> which parses config file
209	for later creation of the Log::Dispatch::Config singleton instance.
210	(Actual construction of the object is done in the first C<instance>
211	call).
212
213	So, what you should do is call C<configure> method once in somewhere
214	(like C<startup.pl> in mod_perl), then you can get configured
215	dispatcher instance via C<Log::Dispatch::Config-E<gt>instance>.
216
217	=head1 CONFIGURATION
218
219	Here is an example of the config file:
220
221	dispatchers = file screen
222
223	file.class = Log::Dispatch::File
224	file.min_level = debug
225	file.filename = /path/to/log
226	file.mode = append
227	file.format = [%d] [%p] %m at %F line %L%n
228
229	screen.class = Log::Dispatch::Screen
230	screen.min_level = info
231	screen.stderr = 1
232	screen.format = %m
233
234	In this example, config file is written in AppConfig format. See
235	L<Log::Dispatch::Configurator::AppConfig> for details.
236
237	See L</"PLUGGABLE CONFIGURATOR"> for other config parsing scheme.
238
239	=head2 GLOBAL PARAMETERS
240
241	=over 4
242
243	=item dispatchers
244
245	dispatchers = file screen
246
247	C<dispatchers> defines logger names, which will be splitted by spaces.
248	If this parameter is unset, no logging is done.
249
250	=item format
251
252	format = [%d] [%p] %m at %F line %L%n
253
254	C<format> defines log format. Possible conversions format are
255
256	%d datetime string (ctime(3))
257	%p priority (debug, info, warning ...)
258	%m message string
259	%F filename
260	%L line number
261	%P package
262	%n newline (\n)
263	%% % itself
264
265	Note that datetime (%d) format is configurable by passing C<strftime>
266	fmt in braket after %d. (I know it looks quite messy, but its
267	compatible with Java Log4j ;)
268
269	format = [%d{%Y%m%d}] %m # datetime is now strftime "%Y%m%d"
270
271	If you have Time::Piece, this module uses its C<strftime>
272	implementation, otherwise POSIX.
273
274	C<format> defined here would apply to all the log messages to
275	dispatchers. This parameter is B<optional>.
276
277	See L</"CALLER STACK"> for details about package, line number and
278	filename.
279
280	=back
281
282	=head2 PARAMETERS FOR EACH DISPATCHER
283
284	Parameters for each dispatcher should be prefixed with "name.", where
285	"name" is the name of each one, defined in global C<dispatchers>
286	parameter.
287
288	You can also use C<.ini> style grouping like:
289
290	[foo]
291	class = Log::Dispatch::File
292	min_level = debug
293
294	See L<Log::Dispatch::Configurator::AppConfig> for details.
295
296	=over 4
297
298	=item class
299
300	screen.class = Log::Dispatch::Screen
301
302	C<class> defines class name of Log::Dispatch subclasses. This
303	parameter is B<essential>.
304
305	=item format
306
307	screen.format = -- %m --
308
309	C<format> defines log format which would be applied only to the
310	dispatcher. Note that if you define global C<format> also, C<%m> is
311	double formated (first global one, next each dispatcher one). This
312	parameter is B<optional>.
313
314	=item (others)
315
316	screen.min_level = info
317	screen.stderr = 1
318
319	Other parameters would be passed to the each dispatcher
320	construction. See Log::Dispatch::* manpage for the details.
321
322	=back
323
324	=head1 SINGLETON
325
326	Declared C<instance> method would make C<Log::Dispatch::Config> class
327	singleton, so multiple calls of C<instance> will all result in
328	returning same object.
329
330	my $one = Log::Dispatch::Config->instance;
331	my $two = Log::Dispatch::Config->instance; # same as $one
332
333	See GoF Design Pattern book for Singleton Pattern.
334
335	But in practice, in persistent environment like mod_perl, lifetime of
336	Singleton instance becomes sometimes messy. If you want to reload
337	singleton object manually, call C<reload> method.
338
339	Log::Dispatch::Config->reload;
340
341	And, if you want to reload object on the fly, as you edit C<log.conf>
342	or something like that, what you should do is to call
343	C<configure_and_watch> method on Log::Dispatch::Config instead of
344	C<configure>. Then C<instance> call will check mtime of configuration
345	file, and compares it with instanciation time of singleton object. If
346	config file is newer than last instanciation, it will automatically
347	reload object.
348
349	=head1 NAMESPACE COLLISION
350
351	If you use Log::Dispatch::Config in multiple projects on the same perl
352	interpreter (like mod_perl), namespace collision would be a
353	problem. Bizzare thing will happen when you call
354	C<Log::Dispatch::Config-E<gt>configure> multiple times with differenct
355	argument.
356
357	In such cases, what you should do is to define your own logger class.
358
359	package My::Logger;
360	use Log::Dispatch::Config;
361	use base qw(Log::Dispatch::Config);
362
363	Or make wrapper for it. See L<POE::Component::Logger> implementation
364	by Matt Sergeant.
365
366	=head1 PLUGGABLE CONFIGURATOR
367
368	If you pass filename to C<configure> method call, this module handles
369	the config file with AppConfig. You can change config parsing scheme
370	by passing another pluggable configurator object.
371
372	Here is a way to declare new configurator class. The example below is
373	hardwired version equivalent to the one above in L</"CONFIGURATION">.
374
375	=over 4
376
377	=item *
378
379	Inherit from Log::Dispatch::Configurator.
380
381	package Log::Dispatch::Configurator::Hardwired;
382	use base qw(Log::Dispatch::Configurator);
383
384	Declare your own C<new> constructor. Stub C<new> method is defined in
385	Configurator base class, but you want to put parsing method in your
386	own constructor. In this example, we just bless reference. Note that
387	your object should be blessed hash.
388
389	sub new { bless {}, shift }
390
391	=item *
392
393	Implement two required object methods C<get_attrs_global> and
394	C<get_attrs>.
395
396	C<get_attrs_global> should return hash reference of global parameters.
397	C<dispatchers> should be an array reference of names of dispatchers.
398
399	sub get_attrs_global {
400	my $self = shift;
401	return {
402	format => undef,
403	dispatchers => [ qw(file screen) ],
404	};
405	}
406
407	C<get_attrs> accepts name of a dispatcher and should return hash
408	reference of parameters associated with the dispatcher.
409
410	sub get_attrs {
411	my($self, $name) = @_;
412	if ($name eq 'file') {
413	return {
414	class => 'Log::Dispatch::File',
415	min_level => 'debug',
416	filename => '/path/to/log',
417	mode => 'append',
418	format => '[%d] [%p] %m at %F line %L%n',
419	};
420	}
421	elsif ($name eq 'screen') {
422	return {
423	class => 'Log::Dispatch::Screen',
424	min_level => 'info',
425	stderr => 1,
426	format => '%m',
427	};
428	}
429	else {
430	die "invalid dispatcher name: $name";
431	}
432	}
433
434	=item *
435
436	Implement optional C<needs_reload> and C<reload>
437	methods. C<needs_reload> should return boolean value if the object is
438	stale and needs reloading itself. This method will be triggered when
439	you configure logging object with C<configure_and_watch> method.
440
441	Stub config file mtime based C<needs_reload> method is declared in
442	Log::Dispatch::Configurator, so if your config class is based on
443	filesystem files, you do not need to reimplement this.
444
445	If you do not need I<singleton-ness> at all, always return true.
446
447	sub needs_reload { 1 }
448
449	C<reload> method should redo parsing of the config file. Configurator
450	base class has a stub null C<reload> method, so you should better
451	override it.
452
453	See Log::Dispatch::Configurator::AppConfig source code for details.
454
455	=item *
456
457	That's all. Now you can plug your own configurator (Hardwired) into
458	Log::Dispatch::Config. What you should do is to pass configurator
459	object to C<configure> method call instead of config file name.
460
461	use Log::Dispatch::Config;
462	use Log::Dispatch::Configurator::Hardwired;
463
464	my $config = Log::Dispatch::Configurator::Hardwired->new;
465	Log::Dispatch::Config->configure($config);
466
467	=back
468
469	=head1 CALLER STACK
470
471	When you call logging method from your subroutines / methods, caller
472	stack would increase and thus you can't see where the log really comes
473	from.
474
475	package Logger;
476	my $Logger = Log::Dispatch::Config->instance;
477
478	sub logit {
479	my($class, $level, $msg) = @_;
480	$Logger->$level($msg);
481	}
482
483	package main;
484	Logger->logit('debug', 'foobar');
485
486	You can adjust package variable C<$Log::Dispatch::Config::CallerDepth>
487	to increase the caller stack depth. The default value is 0.
488
489	sub logit {
490	my($class, $level, $msg) = @_;
491	local $Log::Dispatch::Config::CallerDepth = 1;
492	$Logger->$level($msg);
493	}
494
495	Note that your log caller's namespace should not match against
496	C</^Log::Dispatch/>, which makes this module confusing.
497
498	=head1 AUTHOR
499
500	Tatsuhiko Miyagawa E<lt>miyagawa@bulknews.netE<gt> with much help from
501	Matt Sergeant E<lt>matt@sergeant.orgE<gt>.
502
503	This library is free software; you can redistribute it and/or modify
504	it under the same terms as Perl itself.
505
506	=head1 SEE ALSO
507
508	L<Log::Dispatch::Configurator::AppConfig>, L<Log::Dispatch>,
509	L<AppConfig>, L<POE::Component::Logger>
510
511	=cut
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