Friday, 26 June 2009

Playing Badminton through Clearpress

Yesterday I launched, finally, my badminton ladder web application for our sports and social club. Initially, I write something about 3 years ago, which used flat csv files and a cgi script for each page, which dealt with generating the html and processing results, and updating the ladder, and....

All not very practical, but at least showed what I could do at the time.

Earlier this year we had a change of hardware for our webservers, and we lost the functionality, due to the time lag of all the files being kept up to date as they changed on the multiple servers. A big problem.

So I decided it was time for a rewrite, which I did using Clearpress (, trialling out git and github at the same time (I like this so much more than sourceforge! and svn).

I have blogged about Clearpress and its MVC framework before, so I won't spend time doing so, but with a little work, the setup used 5 tables in a database to produce a reliable system.

team - stores a team name, wins, losses and gives them a unique identifer
player - stores a player name, email and gives them a unique identifier
player_team - join table for a player to a team
ladder_type - our ladder has three sub ladders, to deal with new teams and those which haven't played for a long time
ladder - links team/position/ladder_type

The whole thing can be found on github


It is currently set up to deploy using a SQLLite database, but in production use, we are using a mysql database, and the schema is there. You just need to modify the config.ini file to use a mysql database, which is supported through clearpress.

So, if you are after a web app badminton ladder, then take a look. It is all available as Open Source (GNU Public Licence).

Next, to create a Tennis Competition app.

Thursday, 11 June 2009

lc(x) - possible bad practice?

use strict; use warnings;

We all use the above, right? Well, certainly we should, and my team does;

Now this always causes a warning to occur when testing an undefined value (exception - if the test is for it to be undef).

my $arrayref = $self->method_returning_array_ref() || [];

Now, assuming that the method will always return an arrayref or undef, I will have an arrayref.

Now, it is common enough (returning stuff from an XML dom for example) that there is actually only 1 thing in the array, so I test against it

if ($arrayref->[0] eq 'yes') {
do something..

Now, if $arrayref->[0] is undef, this always throws an uninitialised variable warning. This normally leads me to change to

if ($arrayref->[0] && $arrayref->[0] eq 'yes') {
do something..

so that I don't spam up the logs with warnings.

However, we discovered today that by lowercasing the $arrayref->[0] variable, this will turn an undef into an empty string (for the conditional), therefore dispensing with any warnings.

if (lc$arrayref->[0] eq 'yes') {
do something..

Is this good or bad coding practice?

Reasons for it to be good
- You do not need an extra conditional just to dispense with the warning
- code less

Reasons for it to be bad
- It doesn't seem right
- The conditional is no longer testing against the pure result
- Are we getting rid of the warning for the wrong reason?
- Does it read correctly?

At this time, it is not something that the code police (perlcritic) seem to think is a bad practice, and certainly will make less code for us. It just seems like we are breaking an unwritten coding rule.