Ubuntu Manpage: Log::Dispatchouli - a simple wrapper around Log::Dispatch

Provided by: liblog-dispatchouli-perl_2.012-1_all

NAME

       Log::Dispatchouli - a simple wrapper around Log::Dispatch

VERSION

       version 2.012

SYNOPSIS

         my $logger = Log::Dispatchouli->new({
           ident     => 'stuff-purger',
           facility  => 'daemon',
           to_stdout => $opt->{print},
           debug     => $opt->{verbose}
         });

         $logger->log([ "There are %s items left to purge...", $stuff_left ]);

         $logger->log_debug("this is extra often-ignored debugging log");

         $logger->log_fatal("Now we will die!!");

DESCRIPTION

       Log::Dispatchouli is a thin layer above Log::Dispatch and meant to make it dead simple to
       add logging to a program without having to think much about categories, facilities,
       levels, or things like that.  It is meant to make logging just configurable enough that
       you can find the logs you want and just easy enough that you will actually log things.

       Log::Dispatchouli can log to syslog (if you specify a facility), standard error or
       standard output, to a file, or to an array in memory.  That last one is mostly useful for
       testing.

       In addition to providing as simple a way to get a handle for logging operations,
       Log::Dispatchouli uses String::Flogger to process the things to be logged, meaning you can
       easily log data structures.  Basically: strings are logged as is, arrayrefs are taken as
       (sprintf format, args), and subroutines are called only if needed.  For more information
       read the String::Flogger docs.

METHODS

new
my $logger = Log::Dispatchouli->new(\%arg);

This returns a new logger, a Log::Dispatchouli object.

Valid arguments are:

ident - the name of the thing logging (mandatory)
to_self - log to the logger object for testing; default: false
to_stdout - log to STDOUT; default: false
to_stderr - log to STDERR; default: false
facility - to which syslog facility to send logs; default: none

to_file - log to PROGRAM_NAME.YYYYMMDD in the log path; default: false
log_file - a leaf name for the file to log to with to_file
log_path - path in which to log to file; defaults to DISPATCHOULI_PATH
environment variable or, failing that, to your system's tmpdir

file_format - this optional coderef is passed the message to be logged
and returns the text to write out

log_pid - if true, prefix all log entries with the pid; default: true
fail_fatal - a boolean; if true, failure to log is fatal; default: true
muted - a boolean; if true, only fatals are logged; default: false
debug - a boolean; if true, log_debug method is not a no-op
defaults to the truth of the DISPATCHOULI_DEBUG env var
quiet_fatal - 'stderr' or 'stdout' or an arrayref of zero, one, or both
fatal log messages will not be logged to these
(default: stderr)
config_id - a name for this logger's config; rarely needed!

The log path is either /tmp or the value of the DISPATCHOULI_PATH env var.

If the DISPATCHOULI_NOSYSLOG env var is true, we don't log to syslog.

log
$logger->log(@messages);

$logger->log(\%arg, @messages);

This method uses String::Flogger on the input, then logs the result. Each message is
flogged individually, then joined with spaces.

If the first argument is a hashref, it will be used as extra arguments to logging. It may
include a "prefix" entry to preprocess the message by prepending a string (if the prefix
is a string) or calling a subroutine to generate a new message (if the prefix is a
coderef).

log_fatal
This behaves like the "log" method, but will throw the logged string as an exception after
logging.

This method can also be called as "fatal", to match other popular logging interfaces. If
you want to override this method, you must override "log_fatal" and not "fatal".

log_debug
This behaves like the "log" method, but will only log (at the debug level) if the logger
object has its debug property set to true.

This method can also be called as "debug", to match other popular logging interfaces. If
you want to override this method, you must override "log_debug" and not "debug".

set_debug
$logger->set_debug($bool);

This sets the logger's debug property, which affects the behavior of "log_debug".

get_debug
This gets the logger's debug property, which affects the behavior of "log_debug".

clear_debug
This method does nothing, and is only useful for Log::Dispatchouli::Proxy objects. See
Methods for Proxy Loggers, below.

set_muted
$logger->set_muted($bool);

This sets the logger's muted property, which affects the behavior of "log".

get_muted
This gets the logger's muted property, which affects the behavior of "log".

clear_muted
This method does nothing, and is only useful for Log::Dispatchouli::Proxy objects. See
Methods for Proxy Loggers, below.

get_prefix
my $prefix = $logger->get_prefix;

This method returns the currently-set prefix for the logger, which may be a string or code
reference or undef. See Logger Prefix.

set_prefix
$logger->set_prefix( $new_prefix );

This method changes the prefix. See Logger Prefix.

clear_prefix
This method clears any set logger prefix. (It can also be called as "unset_prefix", but
this is deprecated. See Logger Prefix.

ident
This method returns the logger's ident.

config_id
This method returns the logger's configuration id, which defaults to its ident. This can
be used to make two loggers equivalent in Log::Dispatchouli::Global so that trying to
reinitialize with a new logger with the same "config_id" as the current logger will not
throw an exception, and will simply do no thing.

dispatcher
This returns the underlying Log::Dispatch object. This is not the method you're looking
for. Move along.

LOGGER PREFIX

       Log messages may be prepended with information to set context.  This can be set at a
       logger level or per log item.  The simplest example is:

         my $logger = Log::Dispatchouli->new( ... );

         $logger->set_prefix("Batch 123: ");

         $logger->log("begun processing");

         # ...

         $logger->log("finished processing");

       The above will log something like:

         Batch 123: begun processing
         Batch 123: finished processing

       To pass a prefix per-message:

         $logger->log({ prefix => 'Sub-Item 234: ' }, 'error!')

         # Logs: Batch 123: Sub-Item 234: error!

       If the prefix is a string, it is prepended to each line of the message.  If it is a
       coderef, it is called and passed the message to be logged.  The return value is logged
       instead.

       Proxy loggers also have their own prefix settings, which accumulate.  So:

         my $proxy = $logger->proxy({ proxy_prefix => 'Subsystem 12: ' });

         $proxy->set_prefix('Page 9: ');

         $proxy->log({ prefix => 'Paragraph 6: ' }, 'Done.');

       ...will log...

         Batch 123: Subsystem 12: Page 9: Paragraph 6: Done.

METHODS FOR SUBCLASSING

   string_flogger
       This method returns the thing on which flog will be called to format log messages.  By
       default, it just returns "String::Flogger"

   env_prefix
       This method should return a string used as a prefix to find environment variables that
       affect the logger's behavior.  For example, if this method returns "XYZZY" then when
       checking the environment for a default value for the "debug" parameter, Log::Dispatchouli
       will first check "XYZZY_DEBUG", then "DISPATCHOULI_DEBUG".

       By default, this method returns "()", which means no extra environment variable is
       checked.

   env_value
         my $value = $logger->env_value('DEBUG');

       This method returns the value for the environment variable suffix given.  For example, the
       example given, calling with "DEBUG" will check "DISPATCHOULI_DEBUG".

METHODS FOR TESTING

   new_tester
         my $logger = Log::Dispatchouli->new_tester( \%arg );

       This returns a new logger that logs only "to_self".  It's useful in testing.  If no
       "ident" arg is provided, one will be generated.  "log_pid" is off by default, but can be
       overridden.

       "\%arg" is optional.

   events
       This method returns the arrayref of events logged to an array in memory (in the logger).
       If the logger is not logging "to_self" this raises an exception.

   clear_events
       This method empties the current sequence of events logged into an array in memory.  If the
       logger is not logging "to_self" this raises an exception.

METHODS FOR PROXY LOGGERS

   proxy
         my $proxy_logger = $logger->proxy( \%arg );

       This method returns a new proxy logger -- an instance of Log::Dispatchouli::Proxy -- which
       will log through the given logger, but which may have some settings localized.

       %arg is optional.  It may contain the following entries:

       proxy_prefix
           This is a prefix that will be applied to anything the proxy logger logs, and cannot be
           changed.

       debug
           This can be set to true or false to change the proxy's "am I in debug mode?"  setting.
           It can be changed or cleared later on the proxy.

   parent
   logger
       These methods return the logger itself.  (They're more useful when called on proxy
       loggers.)

METHODS FOR API COMPATIBILITY

       To provide compatibility with some other loggers, most specifically Log::Contextual, the
       following methods are provided.  You should not use these methods without a good reason,
       and you should never subclass them.  Instead, subclass the methods they call.

       is_debug
           This method calls "get_debug".

       is_info
       is_fatal
           These methods return true.

       info
       fatal
       debug
           These methods redispatch to "log", "log_fatal", and "log_debug" respectively.

AUTHOR

       Ricardo SIGNES <rjbs@cpan.org>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2014 by Ricardo SIGNES.

       This is free software; you can redistribute it and/or modify it under the same terms as
       the Perl 5 programming language system itself.