package Log::Contextual;
-use 5.006;
+# ABSTRACT: Simple logging interface with a contextual log
-$VERSION = '1.000';
+use strict;
+use warnings;
-require Exporter;
+my @levels = qw(debug trace warn info error fatal);
-BEGIN { @ISA = qw(Exporter) }
+use Exporter::Declare;
+use Exporter::Declare::Export::Generator;
+use Data::Dumper::Concise;
+use Scalar::Util 'blessed';
-@EXPORT = qw(set_logger log_debug with_logger);
+use B qw(svref_2object);
-our $Get_Logger;
+sub stash_name {
+ my ($coderef) = @_;
+ ref $coderef or return;
+ my $cv = B::svref_2object($coderef);
+ $cv->isa('B::CV') or return;
+ # bail out if GV is undefined
+ $cv->GV->isa('B::SPECIAL') and return;
-sub set_logger {
- $Get_Logger = $_[0];
+ return $cv->GV->STASH->NAME;
}
-sub log_debug (&) {
- my $log = $Get_Logger->();
- $log->debug($_[0]->())
- if $log->is_debug;
+my @dlog = ((map "Dlog_$_", @levels), (map "DlogS_$_", @levels));
+
+my @log = ((map "log_$_", @levels), (map "logS_$_", @levels));
+
+sub _maybe_export {
+ my ($spec, $target, $name, $new_code) = @_;
+
+ if (my $code = $target->can($name)) {
+
+ # this will warn
+ $spec->add_export("&$name", $new_code)
+ unless (stash_name($code) eq __PACKAGE__);
+ } else {
+ $spec->add_export("&$name", $new_code)
+ }
+}
+
+eval {
+ require Log::Log4perl;
+ die if $Log::Log4perl::VERSION < 1.29;
+ Log::Log4perl->wrapper_register(__PACKAGE__)
+};
+
+# ____ is because tags must have at least one export and we don't want to
+# export anything but the levels selected
+sub ____ { }
+
+exports('____', @dlog, @log, qw( set_logger with_logger ));
+
+export_tag dlog => ('____');
+export_tag log => ('____');
+import_arguments qw(logger package_logger default_logger);
+
+sub router {
+ our $Router_Instance ||= do {
+ require Log::Contextual::Router;
+ Log::Contextual::Router->new
+ }
+}
+
+sub default_import {
+ my ($class) = shift;
+
+ die 'Log::Contextual does not have a default import list';
+
+ ()
+}
+
+sub arg_logger { $_[1] }
+sub arg_levels { $_[1] || [qw(debug trace warn info error fatal)] }
+sub arg_package_logger { $_[1] }
+sub arg_default_logger { $_[1] }
+
+sub before_import {
+ my ($class, $importer, $spec) = @_;
+ my $router = $class->router;
+ my $exports = $spec->exports;
+ my %router_args = (
+ exporter => $class,
+ target => $importer,
+ arguments => $spec->argument_info
+ );
+
+ my @tags = $class->default_import($spec)
+ if $spec->config->{default};
+
+ for (@tags) {
+ die "only tags are supported for defaults at this time"
+ unless $_ =~ /^:(.*)$/;
+
+ $spec->config->{$1} = 1;
+ }
+
+ $router->before_import(%router_args);
+
+ if ($exports->{'&set_logger'}) {
+ die ref($router) . " does not support set_logger()"
+ unless $router->does('Log::Contextual::Role::Router::SetLogger');
+
+ _maybe_export($spec, $importer, 'set_logger',
+ sub { $router->set_logger(@_) },
+ );
+ }
+
+ if ($exports->{'&with_logger'}) {
+ die ref($router) . " does not support with_logger()"
+ unless $router->does('Log::Contextual::Role::Router::WithLogger');
+
+ _maybe_export($spec, $importer, 'with_logger',
+ sub { $router->with_logger(@_) },
+ );
+ }
+
+ my @levels = @{$class->arg_levels($spec->config->{levels})};
+ for my $level (@levels) {
+ if ($spec->config->{log} || $exports->{"&log_$level"}) {
+ _maybe_export(
+ $spec,
+ $importer,
+ "log_$level",
+ sub (&@) {
+ my ($code, @args) = @_;
+ $router->handle_log_request(
+ exporter => $class,
+ caller_package => scalar(caller),
+ caller_level => 1,
+ message_level => $level,
+ message_sub => $code,
+ message_args => \@args,
+ );
+ return @args;
+ },
+ );
+ }
+ if ($spec->config->{log} || $exports->{"&logS_$level"}) {
+ _maybe_export(
+ $spec,
+ $importer,
+ "logS_$level",
+ sub (&@) {
+ my ($code, @args) = @_;
+ $router->handle_log_request(
+ exporter => $class,
+ caller_package => scalar(caller),
+ caller_level => 1,
+ message_level => $level,
+ message_sub => $code,
+ message_args => \@args,
+ );
+ return $args[0];
+ },
+ );
+ }
+ if ($spec->config->{dlog} || $exports->{"&Dlog_$level"}) {
+ _maybe_export(
+ $spec,
+ $importer,
+ "Dlog_$level",
+ sub (&@) {
+ my ($code, @args) = @_;
+ my $wrapped = sub {
+ local $_ = (@_ ? Data::Dumper::Concise::Dumper @_ : '()');
+ &$code;
+ };
+ $router->handle_log_request(
+ exporter => $class,
+ caller_package => scalar(caller),
+ caller_level => 1,
+ message_level => $level,
+ message_sub => $wrapped,
+ message_args => \@args,
+ );
+ return @args;
+ },
+ );
+ }
+ if ($spec->config->{dlog} || $exports->{"&DlogS_$level"}) {
+ _maybe_export(
+ $spec,
+ $importer,
+ "DlogS_$level",
+ sub (&$) {
+ my ($code, $ref) = @_;
+ my $wrapped = sub {
+ local $_ = Data::Dumper::Concise::Dumper($_[0]);
+ &$code;
+ };
+ $router->handle_log_request(
+ exporter => $class,
+ caller_package => scalar(caller),
+ caller_level => 1,
+ message_level => $level,
+ message_sub => $wrapped,
+ message_args => [$ref],
+ );
+ return $ref;
+ });
+ }
+ }
}
-sub with_logger {
- local $Get_Logger = $_[0];
- $_[1]->()
+sub after_import {
+ my ($class, $importer, $spec) = @_;
+ my %router_args = (
+ exporter => $class,
+ target => $importer,
+ arguments => $spec->argument_info
+ );
+ $class->router->after_import(%router_args);
+}
+
+for (qw(set with)) {
+ no strict 'refs';
+ my $sub = "${_}_logger";
+ *{"Log::Contextual::$sub"} = sub {
+ die "$sub is no longer a direct sub in Log::Contextual. "
+ . 'Note that this feature was never tested nor documented. '
+ . "Please fix your code to import $sub instead of trying to use it directly"
+ }
}
1;
__END__
-.:12:44:33:. <@mst> we have a $Get_Logger global that contains a subref
-.:12:45:11:. <@mst> sub log_debug (&) { my $log = $Get_Logger->(); if ($log->is_debug) {
- $log->debug($_[0]->()} } }
-.:13:01:22:. >>@mst<< frew: the other part is we'll need a set_logger function that's global
-.:13:01:26:. >>@mst<< frew: plus a with_logger function
-.:13:01:33:. >>@mst<< frew: that uses local()
-.:13:01:38:. <@mst> that should be enough to make a start
-.:13:01:48:. <@frew> so with_logger is what gives us context?
-.:13:01:57:. <@mst> right
-.:13:02:09:. <@mst> with_logger { $logger }, sub { <run code> };
-.:13:02:29:. <@mst> sub with_logger { local $Get_Logger = $_[0]; $_[1]->() }
-.:13:03:05:. <@mst> amazing how simple this stuff is once you get the paradigm
-.:13:03:13:. <@mst> also consider
-.:13:04:17:. <@mst> package Catalyst::Plugin::LogContextual; use Moose::Role; around
- handle_request => sub { my ($orig, $self) = (shift, shift); my @args = @_;
- with_logger { $self->log } sub { $self->$orig(@args) } };
-.:13:03:43:. <@frew> so why is $G_L a subref instead of just a ref? to allow for lazy
- instantiation or what?
-.:13:06:37:. <@mst> it does the caller introspection there IIRC
-.:13:09:56:. <@mst> I've spent like a year thinking about how to do logging sanely
-.:13:10:17:. <@mst> having it turn out to be this bloody trivial to implement amuses me
-.:13:10:43:. <@frew> mst: I guess that's why thinking about it for a year is worth it :-)
-.:13:12:01:. <@mst> there's a couple other things we'll want, I suspect
-.:13:12:18:. <@mst> like a concept of depth and a category system separate from the logger
-.:13:12:24:. <@mst> but those can be handled later atop this API
-.:13:13:35:. <@frew> so like, logging from the model, logging from the controller, logging from
- the DBIDS part of the model vs the DBIC part of the model ?
-.:13:14:13:. <@mst> that sort of thing
-.:13:14:20:. <@mst> how much of that we can delegate to the logger I dunno yet
+=head1 SYNOPSIS
+
+ use Log::Contextual qw( :log :dlog set_logger with_logger );
+ use Log::Contextual::SimpleLogger;
+ use Log::Log4perl ':easy';
+ Log::Log4perl->easy_init($DEBUG);
+
+ my $logger = Log::Log4perl->get_logger;
+
+ set_logger $logger;
+
+ log_debug { 'program started' };
+
+ sub foo {
+
+ my $minilogger = Log::Contextual::SimpleLogger->new({
+ levels => [qw( trace debug )]
+ });
+
+ my @args = @_;
+
+ with_logger $minilogger => sub {
+ log_trace { 'foo entered' };
+ my ($foo, $bar) = Dlog_trace { "params for foo: $_" } @args;
+ # ...
+ log_trace { 'foo left' };
+ };
+ }
+
+ foo();
+
+Beginning with version 1.008 L<Log::Dispatchouli> also works out of the box
+with C<Log::Contextual>:
+
+ use Log::Contextual qw( :log :dlog set_logger );
+ use Log::Dispatchouli;
+ my $ld = Log::Dispatchouli->new({
+ ident => 'slrtbrfst',
+ to_stderr => 1,
+ debug => 1,
+ });
+
+ set_logger $ld;
+
+ log_debug { 'program started' };
+
+=head1 DESCRIPTION
+
+Major benefits:
+
+=over 2
+
+=item * Efficient
+
+The logging functions take blocks, so if a log level is disabled, the
+block will not run:
+
+ # the following won't run if debug is off
+ log_debug { "the new count in the database is " . $rs->count };
+
+Similarly, the C<D> prefixed methods only C<Dumper> the input if the level is
+enabled.
+
+=item * Handy
+
+The logging functions return their arguments, so you can stick them in
+the middle of expressions:
+
+ for (log_debug { "downloading:\n" . join qq(\n), @_ } @urls) { ... }
+
+=item * Generic
+
+C<Log::Contextual> is an interface for all major loggers. If you log through
+C<Log::Contextual> you will be able to swap underlying loggers later.
+
+=item * Powerful
+
+C<Log::Contextual> chooses which logger to use based on L<< user defined C<CodeRef>s|/LOGGER CODEREF >>.
+Normally you don't need to know this, but you can take advantage of it when you
+need to later.
+
+=item * Scalable
+
+If you just want to add logging to your basic application, start with
+L<Log::Contextual::SimpleLogger> and then as your needs grow you can switch to
+L<Log::Dispatchouli> or L<Log::Dispatch> or L<Log::Log4perl> or whatever else.
+
+=back
+
+This module is a simple interface to extensible logging. It exists to
+abstract your logging interface so that logging is as painless as possible,
+while still allowing you to switch from one logger to another.
+
+It is bundled with a really basic logger, L<Log::Contextual::SimpleLogger>,
+but in general you should use a real logger instead. For something
+more serious but not overly complicated, try L<Log::Dispatchouli> (see
+L</SYNOPSIS> for example.)
+
+=head1 A WORK IN PROGRESS
+
+This module is certainly not complete, but we will not break the interface
+lightly, so I would say it's safe to use in production code. The main result
+from that at this point is that doing:
+
+ use Log::Contextual;
+
+will die as we do not yet know what the defaults should be. If it turns out
+that nearly everyone uses the C<:log> tag and C<:dlog> is really rare, we'll
+probably make C<:log> the default. But only time and usage will tell.
+
+=head1 IMPORT OPTIONS
+
+See L</SETTING DEFAULT IMPORT OPTIONS> for information on setting these project
+wide.
+
+=head2 -logger
+
+When you import this module you may use C<-logger> as a shortcut for
+L</set_logger>, for example:
+
+ use Log::Contextual::SimpleLogger;
+ use Log::Contextual qw( :dlog ),
+ -logger => Log::Contextual::SimpleLogger->new({ levels => [qw( debug )] });
+
+sometimes you might want to have the logger handy for other stuff, in which
+case you might try something like the following:
+
+ my $var_log;
+ BEGIN { $var_log = VarLogger->new }
+ use Log::Contextual qw( :dlog ), -logger => $var_log;
+
+=head2 -levels
+
+The C<-levels> import option allows you to define exactly which levels your
+logger supports. So the default,
+C<< [qw(debug trace warn info error fatal)] >>, works great for
+L<Log::Log4perl>, but it doesn't support the levels for L<Log::Dispatch>. But
+supporting those levels is as easy as doing
+
+ use Log::Contextual
+ -levels => [qw( debug info notice warning error critical alert emergency )];
+
+=head2 -package_logger
+
+The C<-package_logger> import option is similar to the C<-logger> import option
+except C<-package_logger> sets the logger for the current package.
+
+Unlike L</-default_logger>, C<-package_logger> cannot be overridden with
+L</set_logger> or L</with_logger>.
+
+ package My::Package;
+ use Log::Contextual::SimpleLogger;
+ use Log::Contextual qw( :log ),
+ -package_logger => Log::Contextual::WarnLogger->new({
+ env_prefix => 'MY_PACKAGE'
+ });
+
+If you are interested in using this package for a module you are putting on
+CPAN we recommend L<Log::Contextual::WarnLogger> for your package logger.
+
+=head2 -default_logger
+
+The C<-default_logger> import option is similar to the C<-logger> import option
+except C<-default_logger> sets the B<default> logger for the current package.
+
+Basically it sets the logger to be used if C<set_logger> is never called; so
+
+ package My::Package;
+ use Log::Contextual::SimpleLogger;
+ use Log::Contextual qw( :log ),
+ -default_logger => Log::Contextual::WarnLogger->new({
+ env_prefix => 'MY_PACKAGE'
+ });
+
+=head1 SETTING DEFAULT IMPORT OPTIONS
+
+Eventually you will get tired of writing the following in every single one of
+your packages:
+
+ use Log::Log4perl;
+ use Log::Log4perl ':easy';
+ BEGIN { Log::Log4perl->easy_init($DEBUG) }
+
+ use Log::Contextual -logger => Log::Log4perl->get_logger;
+
+You can set any of the import options for your whole project if you define your
+own C<Log::Contextual> subclass as follows:
+
+ package MyApp::Log::Contextual;
+
+ use base 'Log::Contextual';
+
+ use Log::Log4perl ':easy';
+ Log::Log4perl->easy_init($DEBUG)
+
+ sub arg_default_logger { $_[1] || Log::Log4perl->get_logger }
+ sub arg_levels { [qw(debug trace warn info error fatal custom_level)] }
+ sub default_import { ':log' }
+
+ # or maybe instead of default_logger
+ sub arg_package_logger { $_[1] }
+
+ # and almost definitely not this, which is only here for completeness
+ sub arg_logger { $_[1] }
+
+Note the C<< $_[1] || >> in C<arg_default_logger>. All of these methods are
+passed the values passed in from the arguments to the subclass, so you can
+either throw them away, honor them, die on usage, etc. To be clear,
+if you define your subclass, and someone uses it as follows:
+
+ use MyApp::Log::Contextual -default_logger => $foo,
+ -levels => [qw(bar baz biff)];
+
+Your C<arg_default_logger> method will get C<$foo> and your C<arg_levels>
+will get C<[qw(bar baz biff)]>;
+
+Additionally, the C<default_import> method is what happens if a user tries to
+use your subclass with no arguments. The default just dies, but if you'd like
+to change the default to import a tag merely return the tags you'd like to
+import. So the following will all work:
+
+ sub default_import { ':log' }
+
+ sub default_import { ':dlog' }
+
+ sub default_import { qw(:dlog :log ) }
+
+See L<Log::Contextual::Easy::Default> for an example of a subclass of
+C<Log::Contextual> that makes use of default import options.
+
+=head1 FUNCTIONS
+
+=head2 set_logger
+
+ my $logger = WarnLogger->new;
+ set_logger $logger;
+
+Arguments: L</LOGGER CODEREF>
+
+C<set_logger> will just set the current logger to whatever you pass it. It
+expects a C<CodeRef>, but if you pass it something else it will wrap it in a
+C<CodeRef> for you. C<set_logger> is really meant only to be called from a
+top-level script. To avoid foot-shooting the function will warn if you call it
+more than once.
+
+=head2 with_logger
+
+ my $logger = WarnLogger->new;
+ with_logger $logger => sub {
+ if (1 == 0) {
+ log_fatal { 'Non Logical Universe Detected' };
+ } else {
+ log_info { 'All is good' };
+ }
+ };
+
+Arguments: L</LOGGER CODEREF>, C<CodeRef $to_execute>
+
+C<with_logger> sets the logger for the scope of the C<CodeRef> C<$to_execute>.
+As with L</set_logger>, C<with_logger> will wrap C<$returning_logger> with a
+C<CodeRef> if needed.
+
+=head2 log_$level
+
+Import Tag: C<:log>
+
+Arguments: C<CodeRef $returning_message, @args>
+
+C<log_$level> functions all work the same except that a different method
+is called on the underlying C<$logger> object. The basic pattern is:
+
+ sub log_$level (&@) {
+ if ($logger->is_$level) {
+ $logger->$level(shift->(@_));
+ }
+ @_
+ }
+
+Note that the function returns it's arguments. This can be used in a number of
+ways, but often it's convenient just for partial inspection of passthrough data
+
+ my @friends = log_trace {
+ 'friends list being generated, data from first friend: ' .
+ Dumper($_[0]->TO_JSON)
+ } generate_friend_list();
+
+If you want complete inspection of passthrough data, take a look at the
+L</Dlog_$level> functions.
+
+Which functions are exported depends on what was passed to L</-levels>. The
+default (no C<-levels> option passed) would export:
+
+=over 2
+
+=item log_trace
+
+=item log_debug
+
+=item log_info
+
+=item log_warn
+
+=item log_error
+
+=item log_fatal
+
+=back
+
+=head2 logS_$level
+
+Import Tag: C<:log>
+
+Arguments: C<CodeRef $returning_message, Item $arg>
+
+This is really just a special case of the L</log_$level> functions. It forces
+scalar context when that is what you need. Other than that it works exactly
+same:
+
+ my $friend = logS_trace {
+ 'I only have one friend: ' . Dumper($_[0]->TO_JSON)
+ } friend();
+
+See also: L</DlogS_$level>.
+
+=head2 Dlog_$level
+
+Import Tag: C<:dlog>
+
+Arguments: C<CodeRef $returning_message, @args>
+
+All of the following six functions work the same as their L</log_$level>
+brethren, except they return what is passed into them and put the stringified
+(with L<Data::Dumper::Concise>) version of their args into C<$_>. This means
+you can do cool things like the following:
+
+ my @nicks = Dlog_debug { "names: $_" } map $_->value, $frew->names->all;
+
+and the output might look something like:
+
+ names: "fREW"
+ "fRIOUX"
+ "fROOH"
+ "fRUE"
+ "fiSMBoC"
+
+Which functions are exported depends on what was passed to L</-levels>. The
+default (no C<-levels> option passed) would export:
+
+=over 2
+
+=item Dlog_trace
+
+=item Dlog_debug
+
+=item Dlog_info
+
+=item Dlog_warn
+
+=item Dlog_error
+
+=item Dlog_fatal
+
+=back
+
+=head2 DlogS_$level
+
+Import Tag: C<:dlog>
+
+Arguments: C<CodeRef $returning_message, Item $arg>
+
+Like L</logS_$level>, these functions are a special case of L</Dlog_$level>.
+They only take a single scalar after the C<$returning_message> instead of
+slurping up (and also setting C<wantarray>) all the C<@args>
+
+ my $pals_rs = DlogS_debug { "pals resultset: $_" }
+ $schema->resultset('Pals')->search({ perlers => 1 });
+
+=head1 LOGGER CODEREF
+
+Anywhere a logger object can be passed, a coderef is accepted. This is so
+that the user can use different logger objects based on runtime information.
+The logger coderef is passed the package of the caller, and the caller level the
+coderef needs to use if it wants more caller information. The latter is in
+a hashref to allow for more options in the future.
+
+Here is a basic example of a logger that exploits C<caller> to reproduce the
+output of C<warn> with a logger:
+
+ my @caller_info;
+ my $var_log = Log::Contextual::SimpleLogger->new({
+ levels => [qw(trace debug info warn error fatal)],
+ coderef => sub { chomp($_[0]); warn "$_[0] at $caller_info[1] line $caller_info[2].\n" }
+ });
+ my $warn_faker = sub {
+ my ($package, $args) = @_;
+ @caller_info = caller($args->{caller_level});
+ $var_log
+ };
+ set_logger($warn_faker);
+ log_debug { 'test' };
+
+The following is an example that uses the information passed to the logger
+coderef. It sets the global logger to C<$l3>, the logger for the C<A1>
+package to C<$l1>, except the C<lol> method in C<A1> which uses the C<$l2>
+logger and lastly the logger for the C<A2> package to C<$l2>.
+
+Note that it increases the caller level as it dispatches based on where
+the caller of the log function, not the log function itself.
+
+ my $complex_dispatcher = do {
+
+ my $l1 = ...;
+ my $l2 = ...;
+ my $l3 = ...;
+
+ my %registry = (
+ -logger => $l3,
+ A1 => {
+ -logger => $l1,
+ lol => $l2,
+ },
+ A2 => { -logger => $l2 },
+ );
+
+ sub {
+ my ( $package, $info ) = @_;
+
+ my $logger = $registry{'-logger'};
+ if (my $r = $registry{$package}) {
+ $logger = $r->{'-logger'} if $r->{'-logger'};
+ my (undef, undef, undef, $sub) = caller($info->{caller_level} + 1);
+ $sub =~ s/^\Q$package\E:://g;
+ $logger = $r->{$sub} if $r->{$sub};
+ }
+ return $logger;
+ }
+ };
+
+ set_logger $complex_dispatcher;
+
+=head1 LOGGER INTERFACE
+
+Because this module is ultimately pretty looking glue (glittery?) with the
+awesome benefit of the Contextual part, users will often want to make their
+favorite logger work with it. The following are the methods that should be
+implemented in the logger:
+
+ is_trace
+ is_debug
+ is_info
+ is_warn
+ is_error
+ is_fatal
+ trace
+ debug
+ info
+ warn
+ error
+ fatal
+
+The first six merely need to return true if that level is enabled. The latter
+six take the results of whatever the user returned from their coderef and log
+them. For a basic example see L<Log::Contextual::SimpleLogger>.
+
+=head1 LOG ROUTING
+
+In between the loggers and the log functions is a log router that is responsible for
+finding a logger to handle the log event and passing the log information to the
+logger. This relationship is described in the documentation for C<Log::Contextual::Role::Router>.
+
+C<Log::Contextual> and packages that extend it will by default share a router singleton that
+implements the with_logger() and set_logger() functions and also respects the -logger,
+-package_logger, and -default_logger import options with their associated default value
+functions. The router singleton is available as the return value of the router() function. Users
+of Log::Contextual may overload router() to return instances of custom log routers that
+could for example work with loggers that use a different interface.
+
+=head1 CONTRIBUTORS
+
+=encoding utf8
+
+triddle - Tyler Riddle <t.riddle@shadowcat.co.uk>
+
+voj - Jakob Voß <voss@gbv.de>
+
+=head1 DESIGNER
+
+mst - Matt S. Trout <mst@shadowcat.co.uk>
+
+=cut
projects / p5sagit/Log-Contextual.git / blobdiff