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For 2023 - 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 Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own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))
Debugging and Data::Dumper in Perl

I'll admit it - I'm not a great fan of debuggers, preferring to write well structured code, and check it out with a few test / intermediate print statements. You'll often find I code:
    $trace and print (something);
in Perl, and this allows me to add a line
    $trace=1;
at the head of my program to turn my own tuned debug mode on, then to comment the line out (or set the variable to zero) to turn my debug mode off.

There are, though, a few occasions where even I will admit that the -d option to Perl - calling in the debugger - can be useful.

I was also reminded on Friday of the Data::Dumper module, which allows you to convert the contents of a variable into a printable string of source code - in other words to let you display a variable's content. The module is shipped with Perl, and will even dump out objects. Here's an example of it in use:

use Data::Dumper;
print Dumper($rover);


And some output from that:

$VAR1 = bless( {
  'breed' => 'Parrot',
  'hf' => 4,
  'name' => 'Rover',
  'age' => 12
  }, 'beast' );


The full source code is here with the Perl module it uses available here
(written 2008-11-02, updated 2008-11-01)

 
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)
  [2229] Do not re-invent the wheel - use a Perl module - (2009-06-11)
  [2234] Loading external code into Perl from a nonstandard directory - (2009-06-12)
  [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)

P203 - More about the Perl Environment
  [328] Making programs easy for any user to start - (2005-05-29)
  [743] How to debug a Perl program - (2006-06-04)
  [748] Getting rid of variables after you have finished with them - (2006-06-06)
  [2876] Different perl examples - some corners I rarely explore - (2010-07-18)


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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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