Random_Walk has asked for the wisdom of the Perl Monks concerning the following question:
So I want a logger object, and only one logger object thought it may be used in various packages. I follow the simple instructions at https://www.perl.com/article/52/2013/12/11/Implementing-the-singleton-pattern-in-Perl but when I test it I see I get two objects. In the following test one gets its 'Log' value altered and the other does not ...
The test ...
perl -MData::Dumper -Mlib=. -MHelper::Lgr -E' \ $l=Helper::Lgr->getInstance();$l->log(0,"Log1"); \ $z=Helper::Lgr->getInstance();$l->set('Log', 4); \ print Dumper $l; \ print Dumper $z' Get instance called from main Not yet instantiated Sun Dec 29 18:51:08 2019 Log1 Get instance called from main Not yet instantiated $VAR1 = bless( { 'LogName' => 'CommandLine.log', '_continuation' => 0, 'Screen' => 0, 'LogDir' => '/home/random/log', 'fh' => \*Helper::Lgr::__ANONIO__, 'Log' => 4 }, 'Helper::Lgr' ); $VAR1 = bless( { 'LogDir' => '/home/random/log', 'Screen' => 0, 'LogName' => 'CommandLine.log', '_continuation' => 0, 'Log' => 0, 'fh' => \*Helper::Lgr::__ANONIO__ }, 'Helper::Lgr' );
Here is the start of the Logger pm that I am using, the set method is pretty much what you expect,so not reprduced here ...
What simple fact am I missing that I get a fresh logger each time?#!/usr/bin/perl # # Lgr.pm # # Controls both logging to a file and to the screen # you can set a verbosity for each independently # package Helper::Lgr; use strict; use warnings; use v5.10.0; use File::Basename; use File::Path qw(make_path); use FindBin; use Data::Dumper; my $script = basename( $0, '.pl', '.pm' ); # Logger is a classic singleton pattern. We only want one instance in +our code my $instance = undef; sub getInstance { say "Get instance called from ".( caller ); if ($instance) { # Already instantiated, check if we need to chang +e any settings say "Already instantiated"; return $instance; } else { say "Not yet instantiated"; } my $class = shift; my $instance = shift; # settings to use $instance = {} unless $instance; die "$instance is not a hash ref\n" unless ref $instance eq 'HASH' +; bless $instance, $class; # we bless early so we can call methods o +n ourself ... And much more ...
Cheers,
R.
Pereant, qui ante nos nostra dixerunt!
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Replies are listed 'Best First'. | |
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Re: My promiscous singleton
by tobyink (Canon) on Dec 29, 2019 at 18:16 UTC | |
by Random_Walk (Prior) on Dec 30, 2019 at 00:28 UTC | |
Re: My promiscous singleton
by kikuchiyo (Hermit) on Dec 29, 2019 at 18:09 UTC | |
by Random_Walk (Prior) on Dec 30, 2019 at 00:26 UTC | |
Re: My promiscous singleton
by 1nickt (Canon) on Dec 29, 2019 at 18:07 UTC | |
by Random_Walk (Prior) on Dec 29, 2019 at 23:40 UTC | |
by afoken (Chancellor) on Dec 30, 2019 at 09:32 UTC | |
by Random_Walk (Prior) on Dec 31, 2019 at 09:41 UTC |
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