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Loading external code into Perl from a nonstandard directory

Here's a piece of Perl code that loads in an external module.

push(@INC, "/var/opt/OV/bin/OpC/monitor");
eval { require "monitor_utils.pm"; };
if ($@) {
  print STDERR "could not load monitor_utils.pm: $@\n";
  exit 1; }


It comes from a delegate's existing application, and is worthy of further comment:

• The @INC list is the places from which Perl loads modules, and the code adds an extra place to that list.

require rather than use pulls the module in, since use happens at compile time, and so would happen BEFORE the extension to @INC.

• The require is within an eval so that any error condition can be trapped, rather than the code crashing, if it failed.

$@ is the error report from the eval. If it's empty, that's good news.

• the application exits with a '1' error code if the require fails - at OS level, 1 is an error and 0 is a success.
(written 2009-06-12)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
P219 - Perl - Libraries and Resources
  [3377] What do I mean when I add things in Perl? - (2011-08-02)
  [3101] The week before Christmas - (2010-12-23)
  [3009] Expect in Perl - a short explanation and a practical example - (2010-10-22)
  [2931] Syncronise - software, trains, and buses. Please! - (2010-08-22)
  [2427] Operator overloading - redefining addition and other Perl tricks - (2009-09-27)
  [2229] Do not re-invent the wheel - use a Perl module - (2009-06-11)
  [1865] Debugging and Data::Dumper in Perl - (2008-11-02)
  [1863] About dieing and exiting in Perl - (2008-11-01)
  [1444] Using English can slow you right down! - (2007-11-25)
  [1391] Ordnance Survey Grid Reference to Latitude / Longitude - (2007-10-14)
  [1235] Outputting numbers as words - MySQL with Perl or PHP - (2007-06-17)
  [1219] Judging the quality of contributed Perl code - (2007-06-06)
  [760] Self help in Perl - (2006-06-14)
  [737] Coloured text in a terminal from Perl - (2006-05-29)
  [712] Why reinvent the wheel - (2006-05-06)
  [358] Use standard Perl modules - (2005-06-25)
  [357] Where do Perl modules load from - (2005-06-24)
  [112] Avoid the wheel being re-invented by using Perl modules - (2004-11-08)
  [86] Talk review - Idiomatic Perl, David Cross - (2004-10-12)


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