Ravendark has asked for the wisdom of the Perl Monks concerning the following question:

Hi all, I have an array of 600 elements (indices of interfaces) and 10 ini-style files. each ini-style file has the form: 
[2287]
slot = 20
port = 1

[download]
each one of them having 60 sections (which represent 60 ports of a machine.) and I have a piece of code that takes an ifindex and stores the values of slot & port into two separate arrays. 
sub translate_ifindex() {
    my $ports_ini_dir = "/home/portal/bin/conf/snmp_set";
    my $slot;
    my $port;
    for ($t = 0; $t < @ifindex; $t++) {
        #print "IFINDEX: $ifindex[$t]\n";
        if ($ifindex[$t] >= 204 && $ifindex[$t] <= 381) {
            my $cfg = new Config::IniFiles( -file => "$ports_ini_dir/s
+nmp_ports_slot02.txt" );
            $slot = $cfg->val("$ifindex[$t]", "slot");
            $port = $cfg->val("$ifindex[$t]", "port");
            push @msan_slot, $slot;
            push @msan_port, $port;
        }
        if ($ifindex[$t] >= 22 && $ifindex[$t] <= 199) {
            my $cfg = new Config::IniFiles( -file => "$ports_ini_dir/s
+nmp_ports_slot04.txt" );
            $slot = $cfg->val("$ifindex[$t]", "slot");
            $port = $cfg->val("$ifindex[$t]", "port");
            push @msan_slot, $slot;
            push @msan_port, $port;
        }
        if ($ifindex[$t] >= 513 && $ifindex[$t] <= 690) {
            my $cfg = new Config::IniFiles( -file => "$ports_ini_dir/s
+nmp_ports_slot06.txt" );
            $slot = $cfg->val("$ifindex[$t]", "slot");
            $port = $cfg->val("$ifindex[$t]", "port");
            push @msan_slot, $slot;
            push @msan_port, $port;
        }
        if ($ifindex[$t] >= 823 && $ifindex[$t] <= 1000) {
            my $cfg = new Config::IniFiles( -file => "$ports_ini_dir/s
+nmp_ports_slot08.txt" );
            $slot = $cfg->val("$ifindex[$t]", "slot");
            $port = $cfg->val("$ifindex[$t]", "port");
            push @msan_slot, $slot;
            push @msan_port, $port;
        }
        if ($ifindex[$t] >= 1067 && $ifindex[$t] <= 1244) {
            my $cfg = new Config::IniFiles( -file => "$ports_ini_dir/s
+nmp_ports_slot10.txt" );
            $slot = $cfg->val("$ifindex[$t]", "slot");
            $port = $cfg->val("$ifindex[$t]", "port");
            push @msan_slot, $slot;
            push @msan_port, $port;
        }
        if ($ifindex[$t] >= 1311 && $ifindex[$t] <= 1488) {
            my $cfg = new Config::IniFiles( -file => "$ports_ini_dir/s
+nmp_ports_slot12.txt" );
            $slot = $cfg->val("$ifindex[$t]", "slot");
            $port = $cfg->val("$ifindex[$t]", "port");
            push @msan_slot, $slot;
            push @msan_port, $port;
        }
        if ($ifindex[$t] >= 1555 && $ifindex[$t] <= 1732) {
            my $cfg = new Config::IniFiles( -file => "$ports_ini_dir/s
+nmp_ports_slot14.txt" );
            $slot = $cfg->val("$ifindex[$t]", "slot");
            $port = $cfg->val("$ifindex[$t]", "port");
            push @msan_slot, $slot;
            push @msan_port, $port;
        }
        if ($ifindex[$t] >= 1799 && $ifindex[$t] <= 1976) {
            my $cfg = new Config::IniFiles( -file => "$ports_ini_dir/s
+nmp_ports_slot16.txt" );
            $slot = $cfg->val("$ifindex[$t]", "slot");
            $port = $cfg->val("$ifindex[$t]", "port");
            push @msan_slot, $slot;
            push @msan_port, $port;
        }
        if ($ifindex[$t] >= 2043 && $ifindex[$t] <= 2220) {
            my $cfg = new Config::IniFiles( -file => "$ports_ini_dir/s
+nmp_ports_slot18.txt" );
            $slot = $cfg->val("$ifindex[$t]", "slot");
            $port = $cfg->val("$ifindex[$t]", "port");
            push @msan_slot, $slot;
            push @msan_port, $port;
        }
        if ($ifindex[$t] >= 2287 && $ifindex[$t] <= 2464) {
            my $cfg = new Config::IniFiles( -file => "$ports_ini_dir/s
+nmp_ports_slot20.txt" );
            $slot = $cfg->val("$ifindex[$t]", "slot");
            $port = $cfg->val("$ifindex[$t]", "port");
            push @msan_slot, $slot;
            push @msan_port, $port;
        }
    }
}

[download]
every time I run it I get this: Can't call method "val" on an undefined value at /home/portal/bin/snmp_set.pl line 142. and line 142 is: $slot = $cfg->val("$ifindex[$t]", "slot"); in the last if statement. If I comment out this section, the program runs without problem. Thanks in advance.

Replies are listed 'Best First'.
Re: Undefined value
by wfsp (Abbot) on Jun 19, 2009 at 12:21 UTC
    First I think I'd check that 
    my $cfg = new Config::IniFiles( -file => "$ports_ini_dir/snmp_ports_sl
+ot20.txt" );

    [download]
    succeeded. Perhaps something like 
    my $cfg_file = q{$ports_ini_dir/snmp_ports_slot20.txt};
my $cfg = Config::IniFiles->new( -file => $cfg_file)
  or die qq{cant open *$cfg_file*: $!};

    [download]
[reply]
[d/l]
[select]
Re: Undefined value
by wfsp (Abbot) on Jun 19, 2009 at 13:13 UTC
    This is similar to Anonymous Monk's suggestion but builds a lookup table. Tables can often simplify your logic and avoid a string of if blocks. 
    #! /usr/bin/perl

use strict;
use warnings;

use Data::Dumper;
$Data::Dumper::Indent = 2;

my @ranges = (
#  low   high  conf_file
  [ 204,  381,  2],
  [  22,  199,  4],
  [ 513,  690,  6],
  [ 823, 1000,  8],
  [1067, 1244, 10],
  [1311, 1488, 12],
  [1555, 1732, 14],
  [1799, 1976, 16],
  [2043, 2220, 18],
  [2287, 2464, 20],
);

my %lookup;
for my $range (@ranges){
  my ($low, $high, $slot) = @{$range};
  for my $index ($low..$high){
    $lookup{$index} = $slot;
  }
}

#print Dumper \%lookup;
#exit;

my @ifindex = (204, 22, 513);
my ($msan_slot, $msan_port) = translate_ifindex(@ifindex);

sub translate_ifindex {
  
  my @ifindex = @_;
  
  my $ports_ini_dir = "/home/portal/bin/conf/snmp_set";
  my (@msan_slot, @msan_port);
  
  for my $t (0..$#ifindex) {
    if (exists $lookup{$t}){
      my $cnf_file = sprintf(q{%s/snmp_ports_slot%02d.txt}, $ports_ini
+_dir, $lookup{$t});
      my $cfg = Config::IniFiles->new( -file => $cnf_file)
        or die q{cant open *$cnf_file*};
      my $slot = $cfg->val($ifindex[$t], "slot");
      my $port = $cfg->val($ifindex[$t], "port");
      push @msan_slot, $slot;
      push @msan_port, $port;
    }
  }
  
  return \@msan_slot, \@msan_port;
  
}

    [download]
    Untested due to not having the config files.

    updated: corrected table syntax and sprintf format string

[reply]
[d/l]
Re: Undefined value
by Anonymous Monk on Jun 19, 2009 at 12:21 UTC
    Why assume Config::IniFiles->new success? Doc say "undef" if the configuration file has an error, in which case check the global @Config::IniFiles::errors array for reasons why
[reply]
      sub translate_ifindex() {
    my $ports_ini_dir = "/home/portal/bin/conf/snmp_set";

    my (@range_files) =
      ( [ 204, 381, "snmp_ports_slot02.txt", ]
        [ 22,   199,  "snmp_ports_slot04.txt", ]
        [ 513,  690,  "snmp_ports_slot06.txt", ]
        [ 823,  1000, "snmp_ports_slot08.txt", ]
        [ 1067, 1244, "snmp_ports_slot10.txt", ]
        [ 1311, 1488, "snmp_ports_slot12.txt", ]
        [ 1555, 1732, "snmp_ports_slot14.txt", ]
        [ 1799, 1976, "snmp_ports_slot16.txt", ]
        [ 2043, 2220, "snmp_ports_slot18.txt", ]
        [ 2287, 2464, "snmp_ports_slot20.txt", ] );

    for ( my $t = 0 ; $t < @ifindex ; $t++ ) {
        for my $range_file (@range_files) {
            if (   $ifindex[$t] >= $$range_file[0]
                && $ifindex[$t] <= $$range_file[1] )
            {
                my $cfg = new Config::IniFiles(
                    -file => "$ports_ini_dir/$$range_file[2]" );
                if ($cfg) {
                    push @msan_slot, $cfg->val( $ifindex[$t], "slot");
                    push @msan_port, $cfg->val( $ifindex[$t], "port");
                }
                else {
                    warn "Ooops($$range_file[2]): @Config::IniFiles::e
+rrors";
                }
            }
        }
    }
}

      [download]
[reply]
[d/l]
      yes it dies... but I cannot figure out why it cannot open the specific file... It was working earlier...
[reply]
        Error message tells you why.
[reply]

Back to Seekers of Perl Wisdom