Use hash variable as constant

Virus2500 has asked for the wisdom of the Perl Monks concerning the following question:

Hello Guys

maybe it is impossible or at least i have no clue how to solve this myself :)

I am trying to load a config file in yaml style (which works). However in the yaml file are some constants which i want to get "translated" by Net::SNMP.

I tried it with an has before which worked a treat

my $snmpConf = (
'.1.3.6.1.4.1.1918.2.13.10.30.80.1.110.2'   =>  { type => INTEGER     
+    , 'value' => '1' }, 
);
[download]

This is the line in the yaml file

.1.3.6.1.4.1.1918.2.13.10.30.80.1.110.2:
  type: INTEGER
  value: "1"
[download]

Reading the values via the oid by snmpget is no problem at all.

However afaik Net::SNMP translates the bareword INTEGER into an integer value... right?
But when i now want to set an variable via snmp it needs to know the type and then it seems like it doesn't get translated to the value anymore.

foreach $oid ( keys $snmpConf) {
$snmp_session->set_request (-varbindlist => [$oid, $snmpConf->{$oid}{t
+ype}, $snmpConf->{$oid}{value}]);
....
[download]

Results in
ERROR: The ASN.1 type "OCTET_STRING" is unknown

So my question is, how can i, if at all, treat $snmpConf->{$oid}{type} like an Constant so it gets translated to the integer value?

tia :)
Mike

Comment on Use hash variable as constant Select or Download Code

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Re: Use hash variable as constant by kcott (Archbishop) on Jun 27, 2014 at 15:50 UTC
G'day Virus2500, Welcome to the monastery. "... which i want to get "translated" by Net::SNMP." You may find some of these (from Net::SNMP's documentation) useful: session() - create a new Net::SNMP object (`-translate` option) translate() - enable or disable the translation mode for the object 3. Non-blocking SNMPv2c get-bulk-request for ifTable (info on default translation and `OCTET_STRING`; sample code) "However afaik Net::SNMP translates the bareword INTEGER into an integer value... right?" You can find the answer to this by tracking back through the code. Doing so will likely increase your understanding of the module and how it works. From source code for Net::SNMP v6.0.1: `use Net::SNMP::PDU qw( :ALL !DEBUG_INFO );` [download] From source code for Net::SNMP::PDU v6.0.1: `use base qw( Net::SNMP::Message ); sub import { return Net::SNMP::Message->export_to_level(1, @_); }` [download] [See Exporter - Exporting Without Using Exporter's import Method for `export_to_level()` doco.] From source code for Net::SNMP::Message v6.0.1: `our %EXPORT_TAGS = ( ... types => [ qw( INTEGER INTEGER32 OCTET_STRING ... ... ); Exporter::export_ok_tags( qw( ... types ... ) ); $EXPORT_TAGS{ALL} = [ @EXPORT_OK ]; ## ASN.1 Basic Encoding Rules type definitions sub INTEGER { 0x02 } # INTEGER sub INTEGER32 { 0x02 } # Integer32 - SNMPv2c sub OCTET_STRING { 0x04 } # OCTET STRING ...` [download] I'll leave you to explore further ... [While reviewing this source code, also look at `sub prepare { ... }`), which contains the source of your error message (i.e. `$_[0]->_error('The ASN.1 type "%s" is unknown', $_[1])`).] "ERROR: The ASN.1 type "OCTET_STRING" is unknown" Net::SNMP exports the symbol `OCTET_STRING` by default. The same is true for `INTEGER`. From source code for Net::SNMP v6.0.1: `use base qw( Exporter ); our @EXPORT = qw( INTEGER INTEGER32 OCTET_STRING ... );` [download] Below this, are other ways to import them: `our %EXPORT_TAGS = ( asn1 => [ qw( INTEGER INTEGER32 OCTET_STRING ... ... Exporter::export_ok_tags( qw( asn1 debug generictrap snmp translate ) +); $EXPORT_TAGS{ALL} = [ @EXPORT_OK ];` [download] [See also: Net::SNMP - EXPORTS] Check how you are loading Net::SNMP; compare that with Net::SNMP - EXAMPLES. [See also: use; Exporter] -- Ken	[reply] [d/l] [select]
Re: Use hash variable as constant by Virus2500 (Initiate) on Jun 27, 2014 at 12:37 UTC
Ok i think i figured it out after reading a lot more. Please correct me if i am wrong. Constants are like subroutines?! So even though i can't access the value directly i can get them via eval. so i added: `my $typeValue = eval("$type()");` [download] and now i am using $typeValue rather than $type itself. Is my understanding of this issue correct? thanks Mike	[reply] [d/l]
Re^2: Use hash variable as constant by kcott (Archbishop) on Jun 27, 2014 at 16:21 UTC
"Is my understanding of this issue correct?" Short answer: I suspect not. Longer answer: Are you talking about the constant pragma? If so, read the doco: you seem to have some (partly) correct, as well as wrong, ideas about this. If you're referring to something else, please specify. -- Ken	[reply]
Re: Use hash variable as constant by RonW (Parson) on Jun 27, 2014 at 16:34 UTC
Update: No. Assuming the YML file had `INTEGER` in it, then `$snmpConf->{$oid}{type}` will just be the string "INTEGER". I think your idea to eval it should work. Maybe: `($snmpConf->{$oid}{type} + 0);` [download]	[reply] [d/l] [select]
Re^2: Use hash variable as constant by Virus2500 (Initiate) on Jun 27, 2014 at 19:29 UTC
Wow thanks to all for your great support. I will dig trough the documentation and source a little bit more. I kinda a thought this might be something "well known" and i am just not aware of it :) However the method i posted with eval is working a treat (if anyone is having the same issue in the future.) thanks again and br Mike	[reply]