Lukasz Wrobel - Blog

Unit Tests - Love, Ignorance and Getting Real

Tue, 09 Feb 2010 23:01:08 +0000

A careful consideration given to unit tests in a form of discussion between spokesmen of three attitudes: "Love", "Ignorance" and "Getting Real".

Which side are you on?

Interpreter Design Pattern

Mon, 07 Dec 2009 21:48:15 +0000

If you're tempted to create your own simple language in order to solve some specialized problem, then the Interpreter design pattern might be a reasonable choice.

Also, if you don't know what the AST tree is or if you're curious what the SQL language and the Interpreter pattern have in common, you should definitely read this article.

RuPy'09 Conference - Agenda is Complete

Sat, 24 Oct 2009 10:26:07 +0000

RuPy is the strongly dynamic conference concerning mostly Ruby and Python programming languages. Registration is open from some time and now we have also completed the agenda. There will be a load of talks and many geek world stars will come to talk about their experiences.

Read on if you're curious who's going to make a speech at RuPy'09.

Rake Tutorial

Tue, 14 Jul 2009 19:33:06 +0000

If you want to learn how to write Rake tasks, this tutorial is right for you!

You're going to learn what the build tools are in general. I will show you how to write your first simple Rake task and how to express dependencies between tasks. I will also cover some useful FileUtils methods.

Get intimate with Rake now!

Obie Fernandez is going to make a presentation at RuPy

Tue, 02 Jun 2009 20:36:10 +0000

We have a first confirmed speaker - Obie Fernandez. Obie is a well-known Ruby on Rails developer and founder of the Hashrocket company. He also keeps a blog and often speaks at conferences.

RuPy 2009 Conference

Fri, 15 May 2009 20:08:08 +0000

Last year I have had the occasion of attending the RuPy Conference. Idea of the community-driven conference took my fancy and I decided to take an active part in the 2009 edition of RuPy.

I cooperate with the RuPy Conference organizers and I will be responsible mainly for keeping the community together. There is also a chance that I'll make a presentation entitled "Artificial Intelligence Methods in Ruby".

If I only get to know something new, I will gladly share the information with you. And if you have any questions regarding the RuPy Conference, do not hesitate to contact me.

Reverse Polish Notation Parser

Sun, 22 Mar 2009 16:19:37 +0000

In the introduction to building a math parser I already mentioned the Reverse Polish notation, also called "postfix notation". Its main advantage is unambiguity: you can simply read expression from left to right and calculate its value at the same time. You have to neither set up operators priorities nor use parenthesis.

There are many implementations of Reverse Polish notation parser available, but most of them seem to be too complicated. So I decided to write a very simple RPNParser Ruby class (RPN comes from "Reverse Polish notation").

RSpec Rake Task

Sat, 21 Feb 2009 15:21:06 +0000

Generally, it is a good idea to automate every boring, complicated programming task that often needs to be repeated. Firstly, developer's time and nerves can be spared. Secondly, the risk of doing something wrong (e.g. making a typo or leaving out one of the steps required) is minimized. Prepare the task once and don't repeat yourself anymore.

There are many tools available and the choice is determined principally by the language and environment we use. Some of the most well-know tools are make, Ant, Phing, Capistrano and Rake. In this short article, we are going to show how to write simple but powerful Rake task to run RSpec tests with code coverage meter.

Ruby Hash Default Value

Sat, 10 Jan 2009 15:11:16 +0000

A Hash in Ruby is a data structure that holds values in the key => value fashion. The Hash class provides many useful methods, some of them come from the Enumerable module. We won't go through all of them now, we'll rather focus on the often forgotten, but worth its value method: default().

We are also going to introduce the Null Object design pattern and show how it can be combined with the default() hash method.

Copy Object in Ruby

Wed, 24 Dec 2008 00:17:54 +0000

Sometimes, when we are working with objects in Ruby, we want to make a copy of them. But what for? Well, in most cases we want to have a working copy and still maintain the original, intact object. Changing a reference back to the primary object is much simpler than repairing object's state.

As we are going to show, Ruby object cloning may sometimes behave in an unexpected way. We are going to show why weird things happen and how to force Ruby to clone objects in the way we want. We will use clone method implementation and marshalling mechanism.