Hello, I am new to Perl and will be very grateful for your patience and assistance.

I am looking for some advice on how to include named args when constructing a new object only if they were specified on the command line.

I am writing a script that uses the Net::SNMP module and I want to have certain optional args, e.g. privpassword and privprotocol, only included when I create the new Net::SNMP object if the user specified a value for them on the command line other than "" (un-used args will be quoted empty, i.e. "").

The script is meant to be called by another program (it's a Cacti plugin FWIW) with position-dependent command line arguments. Here is an example of how my script would be used:

check_snmp.pl 10.0.0.9 admin mypassword https public 2c 161 2500 10 myauthuser myauthpassword sha "" "" "" query portid

My script looks something like this (please note that $user, $pass and $protocol are irrelevant to this question):

use strict;
use warnings;
use Net::SNMP qw(:snmp);

my $address                 = $ARGV[0];
my $user                    = $ARGV[1];
my $pass                    = $ARGV[2];
my $protocol                = lc $ARGV[3];
my $snmp_community          = $ARGV[4];
my $snmp_version            = $ARGV[5];
my $snmp_port               = $ARGV[6];
my $snmp_timeout            = $ARGV[7];
my $max_oids                = $ARGV[8];
my $snmp_username           = $ARGV[9];
my $snmp_password           = $ARGV[10];
my $snmp_auth_protocol      = $ARGV[11];
my $snmp_priv_passphrase    = $ARGV[12];
my $snmp_priv_protocol      = $ARGV[13];
my $snmp_context            = $ARGV[14];
my $action                  = lc $ARGV[15];
my $type                    = lc $ARGV[16];

my ( $session, $error ) = Net::SNMP->session(
    hostname      => $address,
    port          => $snmp_port,
    version       => "snmpv" . $snmp_version,
    timeout       => $snmp_timeout,
    debug         => $snmp_debug_mask,
    username      => $snmp_username,
    authpassword  => $snmp_password,
    authprotocol  => $snmp_auth_protocol,
    privpassword  => $snmp_priv_passphrase,
    privprotocol  => $snmp_priv_protocol,
);

[download]

What I would really like to know is if there are any ways of only including the named arguments when they have been given a value other than "" on the command line?

I tried using an inline if statement, which failed, e.g.

my ( $session, $error ) = Net::SNMP->session(
    ...
    if ($snmp_priv_passphrase ne "") { privpassword  => $snmp_priv_pas
+sphrase, }
    ...
}

[download]

I tried using the arguments undefined, which also failed, e.g.

if ($snmp_priv_passphrase ne "") { $snmp_priv_passphrase = undef; }
my ( $session, $error ) = Net::SNMP->session(
    ...
}

[download]

I know I could put the whole code block inside a series of if statements, so that the named arguments are only included when they have been given a value other than "", but I was wondering if there was a better way of doing it?

Thanks for any help.

In reply to Optionally include named arguments when constructing a new object by nice_iguana

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