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Learn Ruby on Rails: the Ultimate Beginners Tutorial

Sat 14th , February 2009

By: Patrick Lenz


While it certainly makes no attempt to constitute a complete guide to the Ruby language, this tutorial will introduce you to some of the basics of Ruby. We'll power through a crash-course in object oriented programming, covering the more common features of the language along the way, and leaving the more obscure aspects of Ruby for a dedicated reference guide. I'll also point out some of the advantages that Ruby has over other languages when it comes to developing applications for the Web.

Some Rails developers suggest that it's possible to learn and use Rails without learning the Ruby basics first, but as far as I'm concerned, it's extremely beneficial to know even a little Ruby before diving into the guts of Rails. In fact, if you take the time to learn the Ruby basics first, you'll automatically become a better Rails programmer. That's what this tutorial is all about. In fact, this information is excerpted from my new book, Build Your Own Ruby On Rails Web Applications, which is now available through sitepoint.com.

The two chapters presented here get straight into the finer points of Ruby and Rails. If you need installation and other setup instructions, download the sample PDF, which contains chapters 1 to 4. Ruby is a Scripting Language In general, programming languages fall into one of two categories: they're either compiled languages or scripting languages.

Let's explore what each of those terms means, and understand the differences between them. Compiled Languages The language in which you write an application is not actually something that your computer understands. Your code needs to be translated into bits and bytes that can be executed by your computer.

This process of translation is called compilation, and any language that requires compilation is referred to as a compiled language. Examples of compiled languages include C, C#, and Java. For a compiled language, the actual compilation is the final step in the development process. You invoke a compiler -- the software program that translates your final hand-written, human-readable code into machine-readable code -- and the compiler creates an executable file. This final product is then able to execute independently of the original source code. Thus, if you make changes to your code, and you want those changes to be incorporated into the application, you must stop the running application, recompile it, then start the application again. Scripting Languages On the other hand, a scripting language such as Ruby, PHP, or Python, relies upon an application's source code all of the time. Scripting languages don't have a compiler or a compilation phase per se; instead, they use an interpreter -- a program that runs on the web server -- to translate hand-written code into machine-executable code on the fly. The link between the running application and your hand-crafted code is never severed, because that scripting code is translated every time it is invoked -- in other words, for every web page that your application renders. As you might have gathered from the name, the use of an interpreter rather than a compiler is the major difference between a scripting language and a compiled language. The Great Performance Debate If you've come from a compiled-language background, you might be concerned by all this talk of translating code on the fly -- how does it affect the application's performance? These concerns are valid -- translating code on the web server every time it's needed is certainly more expensive, performance-wise, than executing pre-compiled code, as it requires more effort on the part of your machine's processor. The good news is that there are ways to speed up scripted languages, including techniques such as code caching and persistent interpreters. However, both topics are beyond the scope of this book. There's also an upside to scripted languages in terms of performance -- namely, your performance while developing an application. Imagine that you've just compiled a shiny new Java application, and launched it for the first time ... and then you notice a typo on the welcome screen. To fix it, you have to stop your application, go back to the source code, fix the typo, wait for the code to recompile, and restart your application to confirm that it is fixed. And if you find another typo, you'll need to repeat that process again. Lather, rinse, repeat. In a scripting language, you can fix the typo and just reload the page in your browser -- no restart, no recompile, no nothing. It's as simple as that. Ruby is an Object Oriented Language Ruby, from its very beginnings, was built as a programming language that adheres to the principles of object oriented programming (OOP).

Before getting into Ruby specifics, I'd like to introduce you to some fundamental concepts of OOP. Now I know that theory can seem a bit dry to those who are itching to start coding, but we'll cover a lot of ground in this short section, so don't skip it. This discussion will hold you in good stead -- trust me. OOP is a programming paradigm that first surfaced in the 1960s, but didn't gain traction until the 1980s with C . The core idea behind it is that programs should be composed of individual entities, or objects, each of which has the ability to communicate with other objects around it. Additionally, each object may have the facility to store data internally.

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