For 2023 (and 2024 ...) - we are now fully retired from IT training. We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.
Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!
I am also active in many other area and still look after a lot of web sites - you can find an index ((here)) |
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)
Some other Articles
Handling nasty characters - Perl, PHP, Python, Tcl, LuaTaking a pride in the communityAlumni - revisiting and supporting the old UniversitySending awkward characters by email in PerlLoading external code into Perl from a nonstandard directoryTransforming data in Perl using lists of lists and hashes of hashesWhy sendmail one way, and pop3 the other?What is CGI.pm / A dozen new examplesRunning 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
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