1 package Log::Contextual;
6 our $VERSION = '0.004202';
8 my @levels = qw(debug trace warn info error fatal);
10 use Exporter::Declare;
11 use Exporter::Declare::Export::Generator;
12 use Data::Dumper::Concise;
13 use Scalar::Util 'blessed';
15 my @dlog = ((map "Dlog_$_", @levels), (map "DlogS_$_", @levels));
17 my @log = ((map "log_$_", @levels), (map "logS_$_", @levels));
20 require Log::Log4perl;
21 die if $Log::Log4perl::VERSION < 1.29;
22 Log::Log4perl->wrapper_register(__PACKAGE__)
25 # ____ is because tags must have at least one export and we don't want to
26 # export anything but the levels selected
31 qw( set_logger with_logger )
34 export_tag dlog => ('____');
35 export_tag log => ('____');
36 import_arguments qw(logger package_logger default_logger);
39 my ($class, $importer, $spec) = @_;
41 my @tags = $class->default_import($spec)
42 if $spec->config->{default};
45 die "only tags are supported for defaults at this time"
46 unless $_ =~ /^:(.*)$/;
48 $spec->config->{$1} = 1;
51 my @levels = @{$class->arg_levels($spec->config->{levels})};
52 for my $level (@levels) {
53 if ($spec->config->{log}) {
54 $spec->add_export("&log_$level", sub (&@) {
55 _do_log( $level => _get_logger( caller ), shift @_, @_)
57 $spec->add_export("&logS_$level", sub (&@) {
58 _do_logS( $level => _get_logger( caller ), $_[0], $_[1])
61 if ($spec->config->{dlog}) {
62 $spec->add_export("&Dlog_$level", sub (&@) {
63 my ($code, @args) = @_;
64 return _do_log( $level => _get_logger( caller ), sub {
65 local $_ = (@args?Data::Dumper::Concise::Dumper @args:'()');
69 $spec->add_export("&DlogS_$level", sub (&$) {
70 my ($code, $ref) = @_;
71 _do_logS( $level => _get_logger( caller ), sub {
72 local $_ = Data::Dumper::Concise::Dumper $ref;
83 die 'Log::Contextual does not have a default import list';
88 sub arg_logger { $_[1] }
89 sub arg_levels { $_[1] || [qw(debug trace warn info error fatal)] }
90 sub arg_package_logger { $_[1] }
91 sub arg_default_logger { $_[1] }
94 my ($class, $importer, $specs) = @_;
96 if (my $l = $class->arg_logger($specs->config->{logger})) {
100 if (my $l = $class->arg_package_logger($specs->config->{package_logger})) {
101 _set_package_logger_for($importer, $l)
104 if (my $l = $class->arg_default_logger($specs->config->{default_logger})) {
105 _set_default_logger_for($importer, $l)
113 sub _set_default_logger_for {
115 if(ref $logger ne 'CODE') {
116 die 'logger was not a CodeRef or a logger object. Please try again.'
117 unless blessed($logger);
118 $logger = do { my $l = $logger; sub { $l } }
120 $Default_Logger{$_[0]} = $logger
123 sub _set_package_logger_for {
125 if(ref $logger ne 'CODE') {
126 die 'logger was not a CodeRef or a logger object. Please try again.'
127 unless blessed($logger);
128 $logger = do { my $l = $logger; sub { $l } }
130 $Package_Logger{$_[0]} = $logger
136 $Package_Logger{$package} ||
138 $Default_Logger{$package} ||
139 die q( no logger set! you can't try to log something without a logger! )
140 )->($package, { caller_level => 2 });
145 if(ref $logger ne 'CODE') {
146 die 'logger was not a CodeRef or a logger object. Please try again.'
147 unless blessed($logger);
148 $logger = do { my $l = $logger; sub { $l } }
151 warn 'set_logger (or -logger) called more than once! This is a bad idea!'
153 $Get_Logger = $logger;
158 if(ref $logger ne 'CODE') {
159 die 'logger was not a CodeRef or a logger object. Please try again.'
160 unless blessed($logger);
161 $logger = do { my $l = $logger; sub { $l } }
163 local $Get_Logger = $logger;
173 $logger->$level($code->(@_))
174 if $logger->${\"is_$level"};
184 $logger->$level($code->($value))
185 if $logger->${\"is_$level"};
195 Log::Contextual - Simple logging interface with a contextual log
199 use Log::Contextual qw( :log :dlog set_logger with_logger );
200 use Log::Contextual::SimpleLogger;
201 use Log::Log4perl ':easy';
202 Log::Log4perl->easy_init($DEBUG);
204 my $logger = Log::Log4perl->get_logger;
208 log_debug { 'program started' };
212 my $minilogger = Log::Contextual::SimpleLogger->new({
213 levels => [qw( trace debug )]
216 with_logger $minilogger => sub {
217 log_trace { 'foo entered' };
218 my ($foo, $bar) = Dlog_trace { "params for foo: $_" } @_;
220 log_trace { 'foo left' };
226 Beginning with version 1.008 L<Log::Dispatchouli> also works out of the box
227 with C<Log::Contextual>:
229 use Log::Contextual qw( :log :dlog set_logger );
230 use Log::Dispatchouli;
231 my $ld = Log::Dispatchouli->new({
232 ident => 'slrtbrfst',
239 log_debug { 'program started' };
249 The logging functions take blocks, so if a log level is disabled, the
252 # the following won't run if debug is off
253 log_debug { "the new count in the database is " . $rs->count };
255 Similarly, the C<D> prefixed methods only C<Dumper> the input if the level is
260 The logging functions return their arguments, so you can stick them in
261 the middle of expressions:
263 for (log_debug { "downloading:\n" . join qq(\n), @_ } @urls) { ... }
267 C<Log::Contextual> is an interface for all major loggers. If you log through
268 C<Log::Contextual> you will be able to swap underlying loggers later.
272 C<Log::Contextual> chooses which logger to use based on L<< user defined C<CodeRef>s|/LOGGER CODEREF >>.
273 Normally you don't need to know this, but you can take advantage of it when you
278 If you just want to add logging to your extremely basic application, start with
279 L<Log::Contextual::SimpleLogger> and then as your needs grow you can switch to
280 L<Log::Dispatchouli> or L<Log::Dispatch> or L<Log::Log4perl> or whatever else.
284 This module is a simple interface to extensible logging. It exists to
285 abstract your logging interface so that logging is as painless as possible,
286 while still allowing you to switch from one logger to another.
288 It is bundled with a really basic logger, L<Log::Contextual::SimpleLogger>,
289 but in general you should use a real logger instead of that. For something
290 more serious but not overly complicated, try L<Log::Dispatchouli> (see
291 L</SYNOPSIS> for example.)
293 =head1 A WORK IN PROGRESS
295 This module is certainly not complete, but we will not break the interface
296 lightly, so I would say it's safe to use in production code. The main result
297 from that at this point is that doing:
301 will die as we do not yet know what the defaults should be. If it turns out
302 that nearly everyone uses the C<:log> tag and C<:dlog> is really rare, we'll
303 probably make C<:log> the default. But only time and usage will tell.
305 =head1 IMPORT OPTIONS
307 See L</SETTING DEFAULT IMPORT OPTIONS> for information on setting these project
312 When you import this module you may use C<-logger> as a shortcut for
313 L<set_logger>, for example:
315 use Log::Contextual::SimpleLogger;
316 use Log::Contextual qw( :dlog ),
317 -logger => Log::Contextual::SimpleLogger->new({ levels => [qw( debug )] });
319 sometimes you might want to have the logger handy for other stuff, in which
320 case you might try something like the following:
323 BEGIN { $var_log = VarLogger->new }
324 use Log::Contextual qw( :dlog ), -logger => $var_log;
328 The C<-levels> import option allows you to define exactly which levels your
329 logger supports. So the default,
330 C<< [qw(debug trace warn info error fatal)] >>, works great for
331 L<Log::Log4perl>, but it doesn't support the levels for L<Log::Dispatch>. But
332 supporting those levels is as easy as doing
335 -levels => [qw( debug info notice warning error critical alert emergency )];
337 =head2 -package_logger
339 The C<-package_logger> import option is similar to the C<-logger> import option
340 except C<-package_logger> sets the the logger for the current package.
342 Unlike L</-default_logger>, C<-package_logger> cannot be overridden with
346 use Log::Contextual::SimpleLogger;
347 use Log::Contextual qw( :log ),
348 -package_logger => Log::Contextual::WarnLogger->new({
349 env_prefix => 'MY_PACKAGE'
352 If you are interested in using this package for a module you are putting on
353 CPAN we recommend L<Log::Contextual::WarnLogger> for your package logger.
355 =head2 -default_logger
357 The C<-default_logger> import option is similar to the C<-logger> import option
358 except C<-default_logger> sets the the B<default> logger for the current package.
360 Basically it sets the logger to be used if C<set_logger> is never called; so
363 use Log::Contextual::SimpleLogger;
364 use Log::Contextual qw( :log ),
365 -default_logger => Log::Contextual::WarnLogger->new({
366 env_prefix => 'MY_PACKAGE'
369 =head1 SETTING DEFAULT IMPORT OPTIONS
371 Eventually you will get tired of writing the following in every single one of
375 use Log::Log4perl ':easy';
376 BEGIN { Log::Log4perl->easy_init($DEBUG) }
378 use Log::Contextual -logger => Log::Log4perl->get_logger;
380 You can set any of the import options for your whole project if you define your
381 own C<Log::Contextual> subclass as follows:
383 package MyApp::Log::Contextual;
385 use base 'Log::Contextual';
387 use Log::Log4perl ':easy';
388 Log::Log4perl->easy_init($DEBUG)
390 sub arg_default_logger { $_[1] || Log::Log4perl->get_logger }
391 sub arg_levels { [qw(debug trace warn info error fatal custom_level)] }
392 sub default_import { ':log' }
394 # or maybe instead of default_logger
395 sub arg_package_logger { $_[1] }
397 # and almost definitely not this, which is only here for completeness
398 sub arg_logger { $_[1] }
400 Note the C<< $_[1] || >> in C<arg_default_logger>. All of these methods are
401 passed the values passed in from the arguments to the subclass, so you can
402 either throw them away, honor them, die on usage, or whatever. To be clear,
403 if you define your subclass, and someone uses it as follows:
405 use MyApp::Log::Contextual -default_logger => $foo,
406 -levels => [qw(bar baz biff)];
408 Your C<arg_default_logger> method will get C<$foo> and your C<arg_levels>
409 will get C<[qw(bar baz biff)]>;
411 Additionally, the C<default_import> method is what happens if a user tries to
412 use your subclass with no arguments. The default just dies, but if you'd like
413 to change the default to import a tag merely return the tags you'd like to
414 import. So the following will all work:
416 sub default_import { ':log' }
418 sub default_import { ':dlog' }
420 sub default_import { qw(:dlog :log ) }
426 my $logger = WarnLogger->new;
429 Arguments: L</LOGGER CODEREF>
431 C<set_logger> will just set the current logger to whatever you pass it. It
432 expects a C<CodeRef>, but if you pass it something else it will wrap it in a
433 C<CodeRef> for you. C<set_logger> is really meant only to be called from a
434 top-level script. To avoid foot-shooting the function will warn if you call it
439 my $logger = WarnLogger->new;
440 with_logger $logger => sub {
442 log_fatal { 'Non Logical Universe Detected' };
444 log_info { 'All is good' };
448 Arguments: L</LOGGER CODEREF>, C<CodeRef $to_execute>
450 C<with_logger> sets the logger for the scope of the C<CodeRef> C<$to_execute>.
451 As with L</set_logger>, C<with_logger> will wrap C<$returning_logger> with a
452 C<CodeRef> if needed.
458 Arguments: C<CodeRef $returning_message, @args>
460 C<log_$level> functions all work the same except that a different method
461 is called on the underlying C<$logger> object. The basic pattern is:
463 sub log_$level (&@) {
464 if ($logger->is_$level) {
465 $logger->$level(shift->(@_));
470 Note that the function returns it's arguments. This can be used in a number of
471 ways, but often it's convenient just for partial inspection of passthrough data
473 my @friends = log_trace {
474 'friends list being generated, data from first friend: ' .
475 Dumper($_[0]->TO_JSON)
476 } generate_friend_list();
478 If you want complete inspection of passthrough data, take a look at the
479 L</Dlog_$level> functions.
481 Which functions are exported depends on what was passed to L</-levels>. The
482 default (no C<-levels> option passed) would export:
504 Arguments: C<CodeRef $returning_message, Item $arg>
506 This is really just a special case of the L</log_$level> functions. It forces
507 scalar context when that is what you need. Other than that it works exactly
510 my $friend = logS_trace {
511 'I only have one friend: ' . Dumper($_[0]->TO_JSON)
514 See also: L</DlogS_$level>.
520 Arguments: C<CodeRef $returning_message, @args>
522 All of the following six functions work the same as their L</log_$level>
523 brethren, except they return what is passed into them and put the stringified
524 (with L<Data::Dumper::Concise>) version of their args into C<$_>. This means
525 you can do cool things like the following:
527 my @nicks = Dlog_debug { "names: $_" } map $_->value, $frew->names->all;
529 and the output might look something like:
537 Which functions are exported depends on what was passed to L</-levels>. The
538 default (no C<-levels> option passed) would export:
560 Arguments: C<CodeRef $returning_message, Item $arg>
562 Like L</logS_$level>, these functions are a special case of L</Dlog_$level>.
563 They only take a single scalar after the C<$returning_message> instead of
564 slurping up (and also setting C<wantarray>) all the C<@args>
566 my $pals_rs = DlogS_debug { "pals resultset: $_" }
567 $schema->resultset('Pals')->search({ perlers => 1 });
569 =head1 LOGGER CODEREF
571 Anywhere a logger object can be passed, a coderef is accepted. This is so
572 that the user can use different logger objects based on runtime information.
573 The logger coderef is passed the package of the caller the caller level the
574 coderef needs to use if it wants more caller information. The latter is in
575 a hashref to allow for more options in the future.
577 Here is a basic example of a logger that exploits C<caller> to reproduce the
578 output of C<warn> with a logger:
581 my $var_log = Log::Contextual::SimpleLogger->new({
582 levels => [qw(trace debug info warn error fatal)],
583 coderef => sub { chomp($_[0]); warn "$_[0] at $caller_info[1] line $caller_info[2].\n" }
585 my $warn_faker = sub {
586 my ($package, $args) = @_;
587 @caller_info = caller($args->{caller_level});
590 set_logger($warn_faker);
591 log_debug { 'test' };
593 The following is an example that uses the information passed to the logger
594 coderef. It sets the global logger to C<$l3>, the logger for the C<A1>
595 package to C<$l1>, except the C<lol> method in C<A1> which uses the C<$l2>
596 logger and lastly the logger for the C<A2> package to C<$l2>.
598 Note that it increases the caller level as it dispatches based on where
599 the caller of the log function, not the log function itself.
601 my $complex_dispatcher = do {
613 A2 => { -logger => $l2 },
617 my ( $package, $info ) = @_;
619 my $logger = $registry{'-logger'};
620 if (my $r = $registry{$package}) {
621 $logger = $r->{'-logger'} if $r->{'-logger'};
622 my (undef, undef, undef, $sub) = caller($info->{caller_level} + 1);
623 $sub =~ s/^\Q$package\E:://g;
624 $logger = $r->{$sub} if $r->{$sub};
630 set_logger $complex_dispatcher;
632 =head1 LOGGER INTERFACE
634 Because this module is ultimately pretty looking glue (glittery?) with the
635 awesome benefit of the Contextual part, users will often want to make their
636 favorite logger work with it. The following are the methods that should be
637 implemented in the logger:
652 The first six merely need to return true if that level is enabled. The latter
653 six take the results of whatever the user returned from their coderef and log
654 them. For a basic example see L<Log::Contextual::SimpleLogger>.
658 frew - Arthur Axel "fREW" Schmidt <frioux@gmail.com>
662 mst - Matt S. Trout <mst@shadowcat.co.uk>
666 Copyright (c) 2012 the Log::Contextual L</AUTHOR> and L</DESIGNER> as listed
671 This library is free software and may be distributed under the same terms as