Home Accessibility Courses Twitter The Mouth Facebook Resources Site Map About Us Contact
 
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.
How not to write Perl?

You can write a piece of code that resembles a Picasso ... or a piece of code that resembles a dog's dinner ... in Perl. And, rush job yesterday, I wanted to analyse a web access log file and find the number of unique visiting hosts listed. Here's what I came up with:

open (FH,"t09");
while (<FH>) {
  ($j)=split;
  $k{$j}++;
}
@s = keys(%k);
print @s+0,"\n";
foreach $host(sort {$k{$a} <=> $k{$b}} @s) {
  print "$k{$host} $host\n";
}


VERY quick. And VERY dirty, but it works:

[root@p15161732 logs]# perl t09d
291
1 84.16.235.40
1 62.31.153.127
1 86.6.163.203
1 213.40.135.44
[etc]
17 74.6.8.73
25 86.164.206.136
28 194.83.245.226
32 86.151.173.104
55 217.44.22.70
77 82.46.84.146
302 82.33.81.221
[root@p15161732 logs]#


So that's 291 unique hosts, and also some stats on who they are / the distribution of hits.

Why do I question whether or not this is good Perl? Because it will be VERY HARD to maintain later on. Variable names are not descriptive. No comments. No data validation. No checking to see if the input file actually exists. No report on the output as to what it is. No copyright statement / author notes. And that's just or starters.

For a one off - strictly a one off - these things probably don't matter; after all, Perl is the PRACTICAL extraction and reporting language and it did a very practical job of extracting what I needed here!

Learn Perl
The web page I was analysing
(written 2008-01-15, updated 2008-01-16)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
P210 - Perl - Topicalization and Special Variables
  [493] Running a Perl script within a PHP page - (2005-11-12)
  [639] Progress bars and other dynamic reports - (2006-03-09)
  [969] Perl - $_ and @_ - (2006-12-07)
  [1136] Buffering output - why it is done and issues raised in Tcl, Perl, Python and PHP - (2007-04-06)
  [1221] Bathtubs and pecking birds - (2007-06-07)
  [1232] Bathtub example - (2007-06-14)
  [1289] Pure Perl - (2007-08-03)
  [1444] Using English can slow you right down! - (2007-11-25)
  [1704] Finding operating system settings in Perl - (2008-07-10)
  [1705] Environment variables in Perl / use Env - (2008-07-11)
  [1728] A short Perl example - (2008-07-30)
  [1829] Dont bother to write a Perl program - (2008-10-10)
  [1860] Seven new intermediate Perl examples - (2008-10-30)
  [1922] Flurinci knows Raby Lae PHP and Jeve - (2008-12-04)
  [2833] Fresh Perl Teaching Examples - part 2 of 3 - (2010-06-27)
  [2876] Different perl examples - some corners I rarely explore - (2010-07-18)
  [2972] Some more advanced Perl examples from a recent course - (2010-09-27)
  [3449] Apache Internal Dummy Connection - what is it and what should I do with it? - (2011-09-19)
  [4301] Perl - still a very effective language indeed for extracting and reporting - (2014-09-20)
  [4395] Preparing data through a little bit of Perl - (2015-01-15)
  [4682] One line scripts - Awk, Perl and Ruby - (2016-05-20)
  [4700] Obfurscated code - it might work, but is it maintainable? - (2016-07-02)


Back to
Comments on proposed Asda Superstore for Melksham
Previous and next
or
Horse's mouth home
Forward to
Extracting information from a file of records
Some other Articles
Summer Ball at Bowood - Saturday 12th July 2008
Buses from Well House Manor, Melksham, to Bath
Handling Binary data (.gif file example) in Perl
Extracting information from a file of records
How not to write Perl?
Comments on proposed Asda Superstore for Melksham
Ongoing Image Copyright Issues, PHP and MySQL solutions
Script to present commonly used images - PHP
Flooding by Asda-s proposed new supermarket
Web page (http) error status 405
4759 posts, page by page
Link to page ... 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96 at 50 posts per page


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.

Link to Ezine home page (for reading).
Link to Blogging home page (to add comments).

You can Add a comment or ranking to this page

© WELL HOUSE CONSULTANTS LTD., 2021: 48 Spa Road • Melksham, Wiltshire • United Kingdom • SN12 7NY
PH: 01144 1225 708225 • EMAIL: info@wellho.net • WEB: http://www.wellho.net • SKYPE: wellho

PAGE: http://www.wellho.net/mouth/1508_How ... Perl-.html • PAGE BUILT: Sun Oct 11 16:07:41 2020 • BUILD SYSTEM: JelliaJamb