DEVELOPING A BASIC RUBY APPLICATION in Font

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However, this method is only advised if you understand how to navigate your hard drive from the command prompt. Another option, if you re comfortable with creating shortcuts, is to create a shortcut to the Ruby executable file (ruby.exe) and drop your source code file(s) onto it.

The simplest method to run Ruby applications on Mac OS X is from the Terminal, much in the same way as irb is run. The Terminal was explained in 1. If you followed the preceding instructions, continue like so: 1. Launch the Terminal (found in Applications/Utilities). 2. Use cd to navigate to the folder where you placed a.rb like so: cd ~/ruby . This tells the Terminal to take you to the ruby folder located off of your home user folder. 3. Type ruby a.rb and press Enter to execute the a.rb Ruby script. 4. If you get an error such as ruby: No such file or directory -- a.rb (LoadError), you aren t in the same folder as the a.rb source file and need to establish where you have saved it. If you get a satisfactory response from a.rb, you re ready to move on to the section, Our Application: A Text Analyzer.

In Linux or other Unix-based systems, you run your Ruby applications from the shell (that is, within a terminal window) in the same way that you ran irb. The process to run irb was explained in 1, so if you ve forgotten how to get that far, you need to recap yourself before continuing like so: 1. Launch your terminal emulator (xterm, for example) so you get a Linux shell/command prompt. 2. Navigate to the directory where you placed a.rb using the cd command (for example, cd ~/ruby takes you to the ruby directory located directly under your home directory, usually /home/yourusernamehere/). 3. Type ruby a.rb and press Enter to make Ruby execute the a.rb script. If you get a satisfactory response from a.rb, you re ready to move on.

Previously I ve stated that source code is basically the same as plain text. This is true, and although you can write your code in a general text editor, some benefits can be obtained by using a specialist source code editor (or a development IDE Integrated Development Environment). The FreeRIDE editor is an example of an editor specifically created for Ruby developers. It edits text, as with any other text editor, but offers extended features such as source code highlighting and the ability to run code directly from the editor. Some developers find source code syntax highlighting an invaluable feature, as it makes their code easier to read. Variable names, expressions, string literals, and other elements of your source code are all given different colors, which makes it easy to pick them out. Whether you choose a source code editor or a basic text editor depends on your own preference, but it s worth trying both. Many developers prefer the freedom of a regular text editor and then running their Ruby programs from the command line, whereas others prefer to work entirely within a single environment. FreeRIDE is available from http://freeride.rubyforge.org/, and a competing source code editor for Ruby and Rails, called RadRails, is available at http://www.radrails.org/. It s certainly worth investigating these other editors on your platform in case they fit in more with how you wish to work.

The application you re going to develop in this chapter will be a text analyzer. Your Ruby code will read in text supplied in a separate file, analyze it for various patterns and statistics, and print out the results for the user. It s not a 3D graphical adventure or a fancy Web site, but text processing programs are the bread and butter of systems administration and most application development. They can be vital for parsing log files and user-submitted text on Web sites, and manipulating other textual data. Ruby is well suited for text and document analysis with its regular expression features, along with the ease of use of scan and split, and you ll be using these heavily in your application.

Note With this application you ll be focusing on implementing the features quickly, rather than developing an elaborate object-oriented structure, any documentation, or a testing methodology. I ll be covering object orientation and its usage in larger programs in depth in 6, and documentation and testing are covered in 8.