in reply to Re: Dereferencing %hash that does not exist.
in thread Dereferencing %hash that does not exist.

The Dumper output from line 120 should make it clear what $exit_ref will be set to but the error message makes it clear that it is not a code reference. My guess is that my::module::exit_routine(\%modifier) doesn't return a code reference, though it is only a guess as much of your code is not presented.

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Re^3: Dereferencing %hash that does not exist.
by perldarren (Novice) on Sep 04, 2013 at 21:51 UTC 
    Dumper output $VAR1 = \'';

    [download]
    If I remove %modifier and send exit => \&Hitachi::Raidcom::exit_routine there's a whole bunch of $VARS but if I try to add the argument as in this snippet, it breaks.

    Here is the reverse modifier sub and the dispatch table: 

    sub reverse_modifier {
        my (@undo) = @{$_[0]};
        my @rdis;
        my @rdel;
        my @newundo;
        for my $cmd (@undo) {
                if ( $cmd =~ /lock/ ) { push(@newundo, $cmd) }
                if ( $cmd =~ /disconnect/ ) { push (@rdis, $cmd) }
                if ( $cmd =~ /delete/ ) { push (@rdel, $cmd) }
                if ( $cmd =~ /unlock/ ) { push(@newundo,(@rdis,"sleep 
+22",@rdel,$cmd)) }
        }

        return @newundo;
}

my %modifier = ( reverse_modifier => \&reverse_modifier );


# Setup the log object
my $log = LogSimple->new( logdir => $logdir, logfile => $logfile, logl
+evel => $loglevel, verbosity => $verbosity, exit => \&Hitachi::Raidco
+m::exit_routine(\%modifier) );

    [download]
    This is the entire LogSimple module: 
    package LogSimple;

use strict;
use Time::Format qw(%time %strftime %manip);

use Exporter;
use vars qw($VERSION @ISA @EXPORT);

our @ISA = qw(Exporter);

# Items to export into callers namespace by default. Note: do not expo
+rt
# names by default without a very good reason. Use EXPORT_OK instead.
# Do not simply export all your public functions/methods/constants.

# This allows declaration       use LogSimple ':all';
# If you do not need this, moving things directly into @EXPORT or @EXP
+ORT_OK
# will save memory.
our %EXPORT_TAGS = ( 'all' => [ qw(

) ] );

our @EXPORT_OK = ( );

our @EXPORT = qw(

);

our $VERSION = '0.01';

# Preloaded methods go here.

sub new
{
    my $class = shift;
    my %options = @_;

    my $self = {
        _logdir    => 'LogDEC_Dir',
        _logfile   => 'logfile.log',
        _loglevel  => '5',
        _verbosity => '1',
        _script    => $0,
    };

    if ( exists $options{'logdir'} ) {
        $options{'logdir'} =~ s/\///g;
        $self->{_logdir} = $options{'logdir'}
    } else {
        # user didn't specify logdir, tell them where the default was 
+created
        print "Default log directory: $self->{_logdir} - change it to 
+not see this message\n";
    }

    if ( exists $options{'logfile'} ) { $self->{_logfile} = $options{'
+logfile'} };
    if ( exists $options{'loglevel'} ) { $self->{_loglevel} = $options
+{'loglevel'} };
    if ( exists $options{'verbosity'} ) { $self->{_verbosity} = $optio
+ns{'verbosity'} };
    if ( exists $options{'exit'} ) { $self->{_exit} = $options{'exit'}
+ };

    $self->{_log} = "$self->{_logdir}/$self->{_logfile}";

    unless ( -w $self->{_logdir} ) {
        mkdir ( $self->{_logdir}, 0700 ) || die "Unable to create log 
+directory $self->{_logdir}: $!";
    };

    bless $self, $class;
    return $self;
}

sub datetime { return $time{'dd-mm-yyyy_hh.mm.ss'} }

sub inf {
    my ($self,$MESSAGE) = @_; my @PASS;
    push(@PASS,@_); push(@PASS,("","INF", 3));

    wlog(@PASS);
}

sub wrn {
    my ($self,$MESSAGE) = @_; my @PASS;
    push(@PASS,@_); push(@PASS,("","WRN", 2));

    wlog(@PASS);
}

sub dbg {
    my ($self,$MESSAGE) = @_; my @PASS;
    push(@PASS,@_); push(@PASS,("","DBG", 4));

    wlog(@PASS);
}

sub raw {
    my ($self,$MESSAGE) = @_; my @PASS;
    push(@PASS,@_); push(@PASS,("","RAW", 5));

    wlog(@PASS);
}

sub err {
    my ($self,$MESSAGE,$ERR) = @_; my @PASS;
    push(@PASS,@_); push(@PASS,("ERR", 1));

    wlog(@PASS);
}

sub wlog {
    my ($self,$MESSAGE,$ERR,$LEVEL,$LOGLEVEL) = @_;
    my $TIME = datetime();
    my $exit_ref;

    if ( $LOGLEVEL <= $self->{_loglevel} ) {
        open (LOG, ">>$self->{_log}") || warn "Unable to open log file
+ $self->{_log}: $!";
        print LOG "$LEVEL: $TIME : $self->{_script} : $MESSAGE\n";
        print "$LEVEL: $TIME : $self->{_script} : $MESSAGE\n" if ( $se
+lf->{_verbosity} > 0 );
        close (LOG);
    }

    if ( $ERR ) {
        if ( exists $self->{_exit} ) {
        use Data::Dumper;
        print Dumper $self->{_exit};
            $exit_ref = $self->{_exit};
            $exit_ref->($self);
        if ( $LOGLEVEL <= $self->{_loglevel} ) {
        open (LOG, ">>$self->{_log}") || warn "Unable to open log file
+ $self->{_log}: $!";
        print LOG "$LEVEL: $TIME : $self->{_script} : $MESSAGE\n";
        print "$LEVEL: $TIME : $self->{_script} : $MESSAGE\n" if ( $se
+lf->{_verbosity} > 0 );
        close (LOG);
        };
    }

    exit $ERR
    }
}

1;

    [download]
[reply]
[d/l]
[select]

      OK, so Dumper output $VAR1 = \''; shows that $self->{_exit} is not a code ref, as expected. You haven't shown the code of Hitachi::Raidcom::exit_routine, but with the error message and Dumper output, it is reasonably clear what is happening.

      Your code samples seem to be alternating between exit => \&Hitachi::Raidcom::exit_routine(\%modifier) and _exit => my::module::exit_routine(\%modifier), among other alternatives.

      Hitachi::Raidcom::exit_routine(\%modifier) executes the subroutine and yields the value it returns.

      &Hitachi::Raidcom::exit_routine(\%modifier) does the same. The & is optional in this case (with the arguments in parentheses) and makes no difference.

      \&Hitachi::Raidcom::exit_routine(\%modifier) also runs the subroutine and yields a reference to the value it returns. That's why dumper gives you \''. The \ indicates a reference. In this case, a reference to the empty string.

      What will probably work for you is (as AnomalousMonk suggested):

      # Setup the log object
my $log = LogSimple->new( logdir => $logdir, logfile => $logfile, logl
+evel => $loglevel, verbosity => $verbosity, exit => sub { Hitachi::Ra
+idcom::exit_routine(\%modifier) } );

      [download]

      With this initialization, $self->{_exit} should be set to a code reference: to the anonymous sub which does nothing but call Hitachi::Raidcom::exit_routine with the argument \%modifier and return whatever that sub returns. The sub isn't executed immediately. It is executed later, in sub wlog, when the code reference is de-referenced and called. But, I haven't tested...

      While this will probably work for you, I will mention closure (just one of many articles on the subject). It is a confusing feature for many, so I suggest you not worry about it immediately, but once you have this working, learn about closure before making too much use of anonymous subroutines accessing lexical variables.

[reply]
[d/l]
[select]
        Thank you ig, the penny has dropped for me now & I am a step closer to being a better perl programmer. On the strength of my enlightenment I donated $5 to the cause. Thank you to all who assisted me.
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