Perl on Peczenyj's Blog

Adding a 'dry run' capability to your Moose class with MooseX::Role::DryRunnable

Sun, 07 Apr 2013 09:55:00 +0000

A ‘dry run’ is a testing process where the effects of a possible failure are intentionally mitigated. For example, an aerospace company may conduct a “dry run” test of a jet’s new pilot ejection seat while the jet is parked on the ground, rather than while it is in flight. Or, in software development, we can change the behavior of some methods in order to test, like avoid change data into a database (logging the action instead).

There are many ways to implement this capability. For example, we can add an explicity return in each method and test some condition. I will show some options in this article and we will find how to use the module MooseX::Role::DryRunnable in our Moose classes (Perl).

One simple example in Perl, reading from an environment variable DRY_RUN.


package Foo;

sub bar {
	logger->debug("Foo::bar @_");
	return if $ENV{'DRY_RUN'};
	...
}

Lazy::Bool my first module in CPAN

Wed, 23 Jan 2013 20:15:00 +0000

Lazy::Bool is my first module in CPAN (The Comprehensive Perl Archive Network). It is a simple module (only 60 lines) and few methods/operators but can be useful in some situation. The source code can be found in my github.

##Example##

use Lazy::Bool;
use Test::More tests=> 3;
my $a = 6;
my $b = 4;
my $x = Lazy::Bool->new(sub{ $a > $b });
my $false = Lazy::Bool::false;
 
my $result = ($x | $false) & ( ! ( $false & ! $false ) );
 
# now the expressions will be evaluate
ok($result, "complex expression should be true");
ok(!! $x , "double negation of true value should be true"); 
ok(!!! $false, "truple negation of false value should be true");

Schwartzian transform

Tue, 22 Jan 2013 16:00:00 +0000

I will show in this post one of the most useful things that I learn in Perl: the famous Schwartzian transform. With examples in Ruby

In computer science, the Schwartzian transform is a Perl programming idiom used to improve the efficiency of sorting a list of items. This idiom is appropriate for comparison-based sorting when the ordering is actually based on the ordering of a certain property (the key) of the elements, where computing that property is an intensive operation that should be performed a minimal number of times. The Schwartzian Transform is notable in that it does not use named temporary arrays.

TDD com Perl

Fri, 02 May 2008 15:00:00 -0300

É possivel fazer Test Driven Development com Perl? Mas claro :)

Artigo interessante sobre Test::More:
http://www.testingreflections.com/node/view/5333

Tutorial bem sucinto:
http://www.wgz.org/chromatic/perl/IntroTestMore.pdf

Excelente apresentação:
http://wellington.pm.org/archive/200606/tdd/

Comments

Tiago Peczenyj

Trabalho que é coisa séria ninguem comenta... ;-)