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A short Perl example

#!/usr/bin/perl -pa
$_ = "$F[0] $F[-2]\n";

What does that Perl code do?

Although it's very short, it's also somewhat obscure, and my delegates yesterday were not at all sure that they would wish to be given code like this to maintain ... but then they admitted that they have seen things like this around ...

There are some Perl programmers who take what I feel is a perverse delight in writing their code as short as possible, even to the extent that it looses clarity; for sure, you should make good use of the Perl language and its facilities to avoid needless loops - use a grep in place of a foreach loop with a regular expression check and a push, and slurp a file into a list by all means rather that reading in through a while loop - but the above takes it just too far!

Oh - I asked you what it does, didn't I? It reads the file named on the command line in line by line, and prints out the first and next-to-last field on each line, throwing away the rest of the data.
(written 2008-07-30)

 
Associated topics are indexed under
P210 - Perl - Topicalization and Special Variables
  [3449] Apache Internal Dummy Connection - what is it and what should I do with it? - (2011-09-19)
  [2972] Some more advanced Perl examples from a recent course - (2010-09-27)
  [2876] Different perl examples - some corners I rarely explore - (2010-07-18)
  [2833] Fresh Perl Teaching Examples - part 2 of 3 - (2010-06-27)
  [1922] Flurinci knows Raby Lae PHP and Jeve - (2008-12-04)
  [1860] Seven new intermediate Perl examples - (2008-10-30)
  [1829] Dont bother to write a Perl program - (2008-10-10)
  [1705] Environment variables in Perl / use Env - (2008-07-11)
  [1704] Finding operating system settings in Perl - (2008-07-10)
  [1508] How not to write Perl? - (2008-01-15)
  [1444] Using English can slow you right down! - (2007-11-25)
  [1289] Pure Perl - (2007-08-03)
  [1232] Bathtub example - (2007-06-14)
  [1221] Bathtubs and pecking birds - (2007-06-07)
  [1136] Buffering output - why it is done and issues raised in Tcl, Perl, Python and PHP - (2007-04-06)
  [969] Perl - $_ and @_ - (2006-12-07)
  [639] Progress bars and other dynamic reports - (2006-03-09)
  [493] Running a Perl script within a PHP page - (2005-11-12)

P711 - An Introduction to Standards in Perl
  [3398] Perl - making best use of the flexibility, but also using good coding standards - (2011-08-19)
  [2875] A long day in Melksham ... - (2010-07-17)
  [2688] Security considerations in programming - what do we teach? - (2010-03-22)
  [2375] Designing your data structures for a robust Perl application - (2009-08-25)
  [1863] About dieing and exiting in Perl - (2008-11-01)
  [1853] Well structured coding in Perl - (2008-10-24)
  [1555] Advanced Python, Perl, PHP and Tcl training courses / classes - (2008-02-25)
  [1395] Dont just convert to Perl - re-engineer! - (2007-10-18)
  [1345] Perl and Shell coding standards / costs of an IT project - (2007-09-11)
  [1047] Maintainable code - some positive advice - (2007-01-21)
  [965] KISS - one action per statement please - Perl - (2006-12-05)
  [945] Code quality counts - (2006-11-26)
  [743] How to debug a Perl program - (2006-06-04)
  [668] Python - block insets help with documentation - (2006-04-04)
  [242] Satisfaction of training - (2005-03-11)


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