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)

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