1 Getting Started with Ruby

2 What’s Ruby? Ruby is an OO, dynamic, agile language –Everything’s an object For example, try puts -1.abs –Derives strengths of Perl, Smalltalk, Python Created by Matz in mid 90’s Prevalent in Japan; recent buzz in the US It’s a lightweight language –Clean, Higher signal-to-noise ratio There is no compiler to stand in your way Quite flexible–you’ll see when you use it

3 History Created by Yukihiro Matsumoto (Matz) in 1993 Slowly being accepted in the west Popularized by some key players in the industry Gaining strength in various applications –Ruby-On-Rails (ROR)

4 Downloading Ruby Ruby site – For windows, you may use one-click installer

5 Ruby Version You can find the version of ruby you’re using by typing ruby –v

6 Running Ruby Run ruby and type commands Interactively using irb Save code to file and run it I’ll run it directly from notepad2 Other tools and Plugins available as well

7 IDEs Comes with FreeRIDE IDE Mondrian IDE TextPad generally used on Mac Command line and Notepad(2) works great as well! –The following blog entry shows you how –

8 ri RDoc at Documentation…

9 Object-Oriented Ruby treats almost everything as objects nil is an object (try: puts nil.methods) Even classes are objects! –You use them like objects –These objects simply represent their class Pizza is a const that references Pizza class object

10 Code less, do more Java: Ruby Less Clutter GOJ

11 Less Clutter Clean language Less noise ; is not needed Parenthesis are optional Variables don’t have type specification Last statement of a method returns automatically You can even return multiple values!

12 Variables Dynamic typing Output:

13 Types Everything is an object

14 Writing a function

15 Another function Returns an array Assigns elements of array to individual variables

16 Ruby Conventions Conventions are very important Sometimes convention simply makes code look better At other times, it means something significant [you will learn some conventions the hard way ]

17 Class/Method conventions Class names, modules names, and constants start with upper case –SportsCar, ValueOfPI, DAYS_IN_WEEK Methods and variables start with lowercase and use underscore –start_engine(), miles_driven Instance variables Class variables use double ats Global variables use $ –$ozone

18 Method convention talks to you You can figure out what a method is up to from its looks Methods may end with an = –the method may appear as l-value Query method Doesn’t modify object Has side effect; mutates object

19 Global and Predefined Variables This is hideous You may be setting some global variable and not know it (familiarize yourself) Some predefs: $_, $0, $$, $&, $!, …

20 "" vs '' (Double vs. Single Quotes) '' is a simple string Expressions within "" are evaluated Better to use ' if you don’t have expressions

21 More on Strings