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For 2021 - online Python 3 training - see ((here)).

Our plans were to retire in summer 2020 and see the world, but Coronavirus has lead us into a lot of lockdown programming in Python 3 and PHP 7.
We can now offer tailored online training - small groups, real tutors - works really well for groups of 4 to 14 delegates. Anywhere in the world; course language English.

Please ask about private 'maintenance' training for Python 2, Tcl, Perl, PHP, Lua, etc.
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
  [86] Talk review - Idiomatic Perl, David Cross - (2004-10-12)
  [112] Avoid the wheel being re-invented by using Perl modules - (2004-11-08)
  [357] Where do Perl modules load from - (2005-06-24)
  [358] Use standard Perl modules - (2005-06-25)
  [712] Why reinvent the wheel - (2006-05-06)
  [737] Coloured text in a terminal from Perl - (2006-05-29)
  [760] Self help in Perl - (2006-06-14)
  [1219] Judging the quality of contributed Perl code - (2007-06-06)
  [1235] Outputting numbers as words - MySQL with Perl or PHP - (2007-06-17)
  [1391] Ordnance Survey Grid Reference to Latitude / Longitude - (2007-10-14)
  [1444] Using English can slow you right down! - (2007-11-25)
  [1863] About dieing and exiting in Perl - (2008-11-01)
  [1865] Debugging and Data::Dumper in Perl - (2008-11-02)
  [2229] Do not re-invent the wheel - use a Perl module - (2009-06-11)
  [2427] Operator overloading - redefining addition and other Perl tricks - (2009-09-27)
  [2931] Syncronise - software, trains, and buses. Please! - (2010-08-22)
  [3009] Expect in Perl - a short explanation and a practical example - (2010-10-22)
  [3101] The week before Christmas - (2010-12-23)
  [3377] What do I mean when I add things in Perl? - (2011-08-02)


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Alumni - revisiting and supporting the old University
Sending awkward characters by email in Perl
Loading external code into Perl from a nonstandard directory
Transforming data in Perl using lists of lists and hashes of hashes
Why sendmail one way, and pop3 the other?
What is CGI.pm / A dozen new examples
Running a piece of code is like drinking a pint of beer
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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