The Twelve Principles of Agile Software

• Our highest priority is to satisfy the customer through early and continuous delivery of valuable software.
• Welcome changing requirements, even late in development. Agile processes harness change for the customer's competitive advantage.
• Deliver working software frequently, from a couple of weeks to a couple of months, with a preference to the shorter timescale.
• Business people and developers must work together daily throughout the project.
• Build projects around motivated individuals. Give them the environment and support they need, and trust them to get the job done.
• The most efficient and effective method of conveying information to and within a development team is face-to-face conversation.
• Working software is the primary measure of progress.
• Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely.
• Continuous attention to technical excellence and good design enhances agility.
• Simplicity--the art of maximizing the amount of work not done--is essential.
• The best architectures, requirements, and designs emerge from self-organizing teams.
• At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly.

Programming Ruby - The Pragmatic Programmer's Guide

Man is driven to create; I know I really love to create things. And while I'm not good at painting, drawing, or music, I can write software. Shortly after I was introduced to computers, I became interested in programming languages. I believed that an ideal programming language must be attainable, and I wanted to be the designer of it.

Later, after gaining some experience, I realized that this kind of ideal, all-purpose language might be more difficult than I had thought. But I was still hoping to design a language that would work for most of the jobs I did everyday. That was my dream as a student. Years later I talked with colleagues about scripting languages, about their power and possibility. As an object-oriented fan for more than fifteen years, it seemed to me that OO programming was very suitable for scripting too.

I did some research on the 'net for a while, but the candidates I found, Perl and Python, were not exactly what I was looking for. I wanted a language more powerful than Perl, and more object-oriented than Python. Then, I remembered my old dream, and decided to design my own language. At first I was just toying around with it at work. But gradually it grew to be a tool good enough to replace Perl. I named it Ruby--after the precious red stone---and released it to the public in 1995.

Since then a lot of people have become interested in Ruby. Believe it or not, Ruby is actually more popular than Python in Japan right now. I hope that eventually it will be just as well received all over the world. I believe that the purpose of life is, at least in part, to be happy. Based on this belief, Ruby is designed to make programming not only easy, but also fun. It allows you to concentrate on the creative side of programming, with less stress. If you don't believe me, read this book and try Ruby.

I'm sure you'll find out for yourself. I'm very thankful to the people who have joined the Ruby community; they have helped me a lot. I almost feel like Ruby is one of my children, but in fact, it is the result of the combined efforts of many people. Without their help, Ruby could never have become what it is. I am especially thankful to the authors of this book, Dave Thomas and Andy Hunt. Ruby has never been a well-documented language. Because I have always preferred writing programs over writing documents, the Ruby manuals tend to be less thorough than they should be.

You had to read the source to know the exact behavior of the language. But now Dave and Andy have done the work for you. They became interested in a lesser-known language from the Far East. They researched it, read thousands of lines of source code, wrote uncountable test scripts and e-mails, clarified the ambiguous behavior of the language, found bugs (and even fixed some of them), and finally compiled this great book. Ruby is certainly well documented now! Their work on this book has not been trivial. While they were writing it, I was modifying the language itself. But we worked together on the updates, and this book is as accurate as possible. It is my hope that both Ruby and this book will serve to make your programming easy and enjoyable. Have fun!

Yukihiro Matsumoto, a.k.a. ``Matz''

Japan, October 2000

(Reference : http://www.ruby-doc.org)