ch06.080_best

Perl Best Practices the source code

##############################################################################
##   Code fragment (Recommended) from Chapter 6 of "Perl Best Practices"    ##
##     Copyright (c) O'Reilly & Associates, 2005. All Rights Reserved.      ##
##  See: http://www.oreilly.com/pub/a/oreilly/ask_tim/2001/codepolicy.html  ##
##############################################################################


# Standard modules...
use strict;
use warnings;
use IO::Prompt;
use English qw( -no_match_vars );
use Data::Alias;
use Readonly;

BEGIN {

package Debugging;
use Carp;
use Log::Stdlog  { level => 'debug' };

# Choice of actions when debugging...
my %debug_mode = (
  # MODE           DEBUGGING ACTION
    off     => sub {},
    logged  => sub { return print {*STDLOG} debug => @_;   },
    loud    => sub {                 carp 'DEBUG: ', @_; },
    fatal   => sub {                croak 'DEBUG: ', @_; },
    counted =>  do { 
                       my $count = 1;     # Private variable for sub
                       sub { carp "DEBUG: [$count] ", @_; $count++; } 
                   },
);

 
# Change debugging behaviour whenever module is used...
sub import {
    my $package = shift;
    my $mode    = @_ > 0 ? shift : 'loud';   # Default to carping
 
    # Locate appropriate behaviour, or die trying...
    my $debugger = $debug_mode{$mode};
    croak "Unknown debugging mode ('$mode')" if !defined $debugger;
 
    # Install new behaviour...
    use Sub::Installer;
    caller()->reinstall_sub(debug  => $debugger);
 
    return;
}  

}


BEGIN { Debugging->import('counted'); }

debug "Oops!";
debug "Oops!";
debug "Oops!";