600 lines
15 KiB
Perl
600 lines
15 KiB
Perl
package Log::Message;
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use if $] > 5.017, 'deprecate';
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use strict;
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use Params::Check qw[check];
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use Log::Message::Item;
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use Log::Message::Config;
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use Locale::Maketext::Simple Style => 'gettext';
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local $Params::Check::VERBOSE = 1;
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BEGIN {
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use vars qw[$VERSION @ISA $STACK $CONFIG];
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$VERSION = '0.08';
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$STACK = [];
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}
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=pod
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=head1 NAME
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Log::Message - A generic message storing mechanism;
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=head1 SYNOPSIS
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use Log::Message private => 0, config => '/our/cf_file';
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my $log = Log::Message->new( private => 1,
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level => 'log',
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config => '/my/cf_file',
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);
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$log->store('this is my first message');
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$log->store( message => 'message #2',
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tag => 'MY_TAG',
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level => 'carp',
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extra => ['this is an argument to the handler'],
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);
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my @last_five_items = $log->retrieve(5);
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my @items = $log->retrieve( tag => qr/my_tag/i,
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message => qr/\d/,
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remove => 1,
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);
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my @items = $log->final( level => qr/carp/, amount => 2 );
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my $first_error = $log->first()
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# croak with the last error on the stack
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$log->final->croak;
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# empty the stack
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$log->flush();
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=head1 DESCRIPTION
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Log::Message is a generic message storage mechanism.
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It allows you to store messages on a stack -- either shared or private
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-- and assign meta-data to it.
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Some meta-data will automatically be added for you, like a timestamp
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and a stack trace, but some can be filled in by the user, like a tag
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by which to identify it or group it, and a level at which to handle
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the message (for example, log it, or die with it)
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Log::Message also provides a powerful way of searching through items
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by regexes on messages, tags and level.
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=head1 Hierarchy
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There are 4 modules of interest when dealing with the Log::Message::*
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modules:
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=over 4
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=item Log::Message
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Log::Message provides a few methods to manipulate the stack it keeps.
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It has the option of keeping either a private or a public stack.
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More on this below.
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=item Log::Message::Item
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These are individual message items, which are objects that contain
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the user message as well as the meta-data described above.
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See the L<Log::Message::Item> manpage to see how to extract this
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meta-data and how to work with the Item objects.
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You should never need to create your own Item objects, but knowing
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about their methods and accessors is important if you want to write
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your own handlers. (See below)
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=item Log::Message::Handlers
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These are a collection of handlers that will be called for a level
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that is used on a L<Log::Message::Item> object.
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For example, if a message is logged with the 'carp' level, the 'carp'
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handler from L<Log::Message::Handlers> will be called.
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See the L<Log::Message::Handlers> manpage for more explanation about how
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handlers work, which one are available and how to create your own.
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=item Log::Message::Config
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Per Log::Message object, there is a configuration required that will
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fill in defaults if the user did not specify arguments to override
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them (like for example what tag will be set if none was provided),
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L<Log::Message::Config> handles the creation of these configurations.
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Configuration can be specified in 4 ways:
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=over 4
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=item *
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As a configuration file when you C<use Log::Message>
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=item *
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As arguments when you C<use Log::Message>
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=item *
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As a configuration file when you create a new L<Log::Message> object.
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(The config will then only apply to that object if you marked it as
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private)
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=item *
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As arguments when you create a new Log::Message object.
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You should never need to use the L<Log::Message::Config> module yourself,
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as this is transparently done by L<Log::Message>, but its manpage does
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provide an explanation of how you can create a config file.
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=back
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=back
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=head1 Options
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When using Log::Message, or creating a new Log::Message object, you can
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supply various options to alter its behaviour.
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Of course, there are sensible defaults should you choose to omit these
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options.
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Below an explanation of all the options and how they work.
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=over 4
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=item config
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The path to a configuration file to be read.
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See the manpage of L<Log::Message::Config> for the required format
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These options will be overridden by any explicit arguments passed.
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=item private
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Whether to create, by default, private or shared objects.
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If you choose to create shared objects, all Log::Message objects will
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use the same stack.
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This means that even though every module may make its own $log object
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they will still be sharing the same error stack on which they are
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putting errors and from which they are retrieving.
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This can be useful in big projects.
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If you choose to create a private object, then the stack will of
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course be private to this object, but it will still fall back to the
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shared config should no private config or overriding arguments be
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provided.
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=item verbose
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Log::Message makes use of another module to validate its arguments,
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which is called L<Params::Check>, which is a lightweight, yet
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powerful input checker and parser. (See the L<Params::Check>
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manpage for details).
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The verbose setting will control whether this module will
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generate warnings if something improper is passed as input, or merely
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silently returns undef, at which point Log::Message will generate a
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warning.
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It's best to just leave this at its default value, which is '1'
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=item tag
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The tag to add to messages if none was provided. If neither your
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config, nor any specific arguments supply a tag, then Log::Message will
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set it to 'NONE'
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Tags are useful for searching on or grouping by. For example, you
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could tag all the messages you want to go to the user as 'USER ERROR'
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and all those that are only debug information with 'DEBUG'.
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At the end of your program, you could then print all the ones tagged
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'USER ERROR' to STDOUT, and those marked 'DEBUG' to a log file.
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=item level
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C<level> describes what action to take when a message is logged. Just
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like C<tag>, Log::Message will provide a default (which is 'log') if
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neither your config file, nor any explicit arguments are given to
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override it.
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See the Log::Message::Handlers manpage to see what handlers are
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available by default and what they do, as well as to how to add your
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own handlers.
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=item remove
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This indicates whether or not to automatically remove the messages
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from the stack when you've retrieved them.
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The default setting provided by Log::Message is '0': do not remove.
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=item chrono
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This indicates whether messages should always be fetched in
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chronological order or not.
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This simply means that you can choose whether, when retrieving items,
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the item most recently added should be returned first, or the one that
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had been added most long ago.
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The default is to return the newest ones first
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=back
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=cut
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### subs ###
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sub import {
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my $pkg = shift;
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my %hash = @_;
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$CONFIG = new Log::Message::Config( %hash )
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or die loc(qq[Problem initialising %1], __PACKAGE__);
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}
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=head1 Methods
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=head2 new
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This creates a new Log::Message object; The parameters it takes are
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described in the C<Options> section below and let it just be repeated
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that you can use these options like this:
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my $log = Log::Message->new( %options );
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as well as during C<use> time, like this:
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use Log::Message option1 => value, option2 => value
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There are but 3 rules to keep in mind:
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=over 4
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=item *
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Provided arguments take precedence over a configuration file.
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=item *
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Arguments to new take precedence over options provided at C<use> time
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=item *
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An object marked private will always have an empty stack to begin with
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=back
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=cut
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sub new {
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my $class = shift;
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my %hash = @_;
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my $conf = new Log::Message::Config( %hash, default => $CONFIG ) or return undef;
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if( $conf->private || $CONFIG->private ) {
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return _new_stack( $class, config => $conf );
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} else {
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my $obj = _new_stack( $class, config => $conf, stack => $STACK );
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### if it was an empty stack, this was the first object
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### in that case, set the global stack to match it for
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### subsequent new, non-private objects
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$STACK = $obj->{STACK} unless scalar @$STACK;
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return $obj;
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}
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}
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sub _new_stack {
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my $class = shift;
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my %hash = @_;
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my $tmpl = {
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stack => { default => [] },
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config => { default => bless( {}, 'Log::Message::Config'),
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required => 1,
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strict_type => 1
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},
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};
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my $args = check( $tmpl, \%hash, $CONFIG->verbose ) or (
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warn(loc(q[Could not create a new stack object: %1],
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Params::Check->last_error)
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),
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return
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);
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my %self = map { uc, $args->{$_} } keys %$args;
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return bless \%self, $class;
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}
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sub _get_conf {
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my $self = shift;
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my $what = shift;
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return defined $self->{CONFIG}->$what()
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? $self->{CONFIG}->$what()
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: defined $CONFIG->$what()
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? $CONFIG->$what()
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: undef; # should never get here
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}
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=head2 store
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This will create a new Item object and store it on the stack.
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Possible arguments you can give to it are:
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=over 4
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=item message
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This is the only argument that is required. If no other arguments
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are given, you may even leave off the C<message> key. The argument
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will then automatically be assumed to be the message.
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=item tag
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The tag to add to this message. If not provided, Log::Message will look
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in your configuration for one.
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=item level
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The level at which this message should be handled. If not provided,
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Log::Message will look in your configuration for one.
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=item extra
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This is an array ref with arguments passed to the handler for this
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message, when it is called from store();
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The handler will receive them as a normal list
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=back
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store() will return true upon success and undef upon failure, as well
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as issue a warning as to why it failed.
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=cut
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### should extra be stored in the item object perhaps for later retrieval?
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sub store {
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my $self = shift;
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my %hash = ();
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my $tmpl = {
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message => {
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default => '',
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strict_type => 1,
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required => 1,
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},
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tag => { default => $self->_get_conf('tag') },
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level => { default => $self->_get_conf('level'), },
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extra => { default => [], strict_type => 1 },
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};
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### single arg means just the message
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### otherwise, they are named
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if( @_ == 1 ) {
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$hash{message} = shift;
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} else {
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%hash = @_;
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}
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my $args = check( $tmpl, \%hash ) or (
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warn( loc(q[Could not store error: %1], Params::Check->last_error) ),
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return
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);
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my $extra = delete $args->{extra};
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my $item = Log::Message::Item->new( %$args,
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parent => $self,
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id => scalar @{$self->{STACK}}
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)
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or ( warn( loc(q[Could not create new log item!]) ), return undef );
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push @{$self->{STACK}}, $item;
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{ no strict 'refs';
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my $sub = $args->{level};
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$item->$sub( @$extra );
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}
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return 1;
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}
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=head2 retrieve
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This will retrieve all message items matching the criteria specified
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from the stack.
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Here are the criteria you can discriminate on:
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=over 4
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=item tag
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A regex to which the tag must adhere. For example C<qr/\w/>.
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=item level
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A regex to which the level must adhere.
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=item message
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A regex to which the message must adhere.
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=item amount
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Maximum amount of errors to return
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=item chrono
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Return in chronological order, or not?
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=item remove
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Remove items from the stack upon retrieval?
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=back
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In scalar context it will return the first item matching your criteria
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and in list context, it will return all of them.
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If an error occurs while retrieving, a warning will be issued and
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undef will be returned.
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=cut
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sub retrieve {
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my $self = shift;
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my %hash = ();
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my $tmpl = {
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tag => { default => qr/.*/ },
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level => { default => qr/.*/ },
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message => { default => qr/.*/ },
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amount => { default => '' },
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remove => { default => $self->_get_conf('remove') },
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chrono => { default => $self->_get_conf('chrono') },
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};
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### single arg means just the amount
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### otherwise, they are named
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if( @_ == 1 ) {
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$hash{amount} = shift;
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} else {
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%hash = @_;
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}
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my $args = check( $tmpl, \%hash ) or (
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warn( loc(q[Could not parse input: %1], Params::Check->last_error) ),
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return
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);
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my @list =
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grep { $_->tag =~ /$args->{tag}/ ? 1 : 0 }
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grep { $_->level =~ /$args->{level}/ ? 1 : 0 }
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grep { $_->message =~ /$args->{message}/ ? 1 : 0 }
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grep { defined }
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$args->{chrono}
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? @{$self->{STACK}}
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: reverse @{$self->{STACK}};
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my $amount = $args->{amount} || scalar @list;
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my @rv = map {
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$args->{remove} ? $_->remove : $_
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} scalar @list > $amount
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? splice(@list,0,$amount)
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: @list;
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return wantarray ? @rv : $rv[0];
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}
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=head2 first
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This is a shortcut for retrieving the first item(s) stored on the
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stack. It will default to only retrieving one if called with no
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arguments, and will always return results in chronological order.
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If you only supply one argument, it is assumed to be the amount you
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wish returned.
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Furthermore, it can take the same arguments as C<retrieve> can.
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=cut
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sub first {
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my $self = shift;
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my $amt = @_ == 1 ? shift : 1;
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return $self->retrieve( amount => $amt, @_, chrono => 1 );
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}
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=head2 last
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This is a shortcut for retrieving the last item(s) stored on the
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stack. It will default to only retrieving one if called with no
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arguments, and will always return results in reverse chronological
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order.
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If you only supply one argument, it is assumed to be the amount you
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wish returned.
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Furthermore, it can take the same arguments as C<retrieve> can.
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=cut
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sub final {
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my $self = shift;
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my $amt = @_ == 1 ? shift : 1;
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return $self->retrieve( amount => $amt, @_, chrono => 0 );
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}
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=head2 flush
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This removes all items from the stack and returns them to the caller
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=cut
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sub flush {
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my $self = shift;
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return splice @{$self->{STACK}};
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}
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=head1 SEE ALSO
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L<Log::Message::Item>, L<Log::Message::Handlers>, L<Log::Message::Config>
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=head1 AUTHOR
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This module by
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Jos Boumans E<lt>kane@cpan.orgE<gt>.
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=head1 Acknowledgements
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Thanks to Ann Barcomb for her suggestions.
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=head1 COPYRIGHT
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This module is
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copyright (c) 2002 Jos Boumans E<lt>kane@cpan.orgE<gt>.
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All rights reserved.
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This library is free software;
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you may redistribute and/or modify it under the same
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terms as Perl itself.
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=cut
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1;
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# Local variables:
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# c-indentation-style: bsd
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# c-basic-offset: 4
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# indent-tabs-mode: nil
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# End:
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# vim: expandtab shiftwidth=4:
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