package Logger;

$VERSION = 1.00;

use strict;
use vars qw( $AUTOLOAD );
use Data::Dumper;
use Carp;

{
  #Encapsulated class data

    my %_log_attr =  #      DEFAULT       ACCESSIBILITY
        (
          _name         => ['DEFAULT',    'read/write'],
          _handle       => [undef,        'read']
        );

    #is a specirfied object attribute accessible in a given mode
    sub _accessible
    {
      my ($self, $attr, $mode) = @_;
      $_log_attr{$attr}[1] =~ /$mode/
    }

    # Classwide default value for a specified object attributes
    sub _default_for
    {
      my ($self, $attr) = @_;
      $_log_attr{$attr}[2];
    }

    # list of names of all specified object attributes
    sub _standard_keys
    {
      keys %_log_attr;
    }

    # return datestamp
    sub _date {
        my @date=localtime;
        ++$date[4];
        if (length($date[3])eq 1 ) {$date[3]='0'.$date[3]};
        if (length($date[4])eq 1 ) {$date[4]='0'.$date[4]};
        $date[5]=$date[5]+1900;
        return($date[3].$date[4].$date[5],"$date[3]-$date[4]-$date[5]");
    }

    # return timestamp
    sub _time {
        my @time=localtime;
        ++$time[4];
        if (length($time[2])eq 1 ) {$time[2]='0'.$time[2]};
        if (length($time[1])eq 1 ) {$time[1]='0'.$time[1]};

        return($time[2].$time[1].$time[0],"$time[2]:$time[1]:$time[0]");
    }

}

sub new {

    my ($caller, %arg) = @_;
    my $caller_is_obj = ref($caller);
    my $class = $caller_is_obj  || $caller;
    my $self  = bless {}, $class;

    foreach my $attrname ($self->_standard_keys() )
    {
      my ($argname) = ($attrname =~ /^_(.*)/);
      if (exists $arg{$argname})
          { $self->{$attrname} = $arg{$argname} ;
          }
      elsif ($caller_is_obj)
          { $self->{$attrname} = $caller->{$argname};
          }
      else
          { $self->{$attrname} = $self->_default_for($attrname) }
    }

    $self->{_handle}=&prepare_file($self);

    return $self;
}

sub prepare_file {

    my $self = shift;
    if ($self->{_name}) {

        if ($self->{_name} =~ /^[\w\.]+$/) {

            my @ds = $self->_date();
            my $name = '>>'.$self->{_name}.'.'.$ds[0].'.log';

            local*LOGFILE;
            open(LOGFILE, $name) || carp "Unable to open file: $!";

            return *LOGFILE;

        } else {

            carp "You may only use alphanumerics, dot <.> and underscore <_> in names.\n";
            return undef;

        }

    }

}

sub log {

    my ($self, $location, $message) = @_;

    if ($self->{_handle}) {
      print {$self->{_handle}} $self->_date().' '.$self->_time().", $$, $location, $message\n";

    } else {
        carp "Must call logger->new(name=>'<logfile>') before writing log.\n";
    }
}

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