Getting Started with Ruby

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Getting Started with Ruby
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Whats Ruby?

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

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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)

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Downloading Ruby

• Ruby site
• http//www.ruby-lang.org
• For windows, you may use one-click installer
  http//rubyinstaller.rubyforge.org

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Ruby Version

• You can find the version of ruby youre using by
  typing ruby v

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Running Ruby

• Run ruby and type commands
• Interactively using irb
• Save code to file and run it
• Ill run it directly from notepad2
• Other tools and Plugins available as well

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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
• http//tinyurl.com/as8z7

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Documentation

• ri
• RDoc at http//www.ruby-doc.org

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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
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Less Clutter

• Code less, do more
• Java
• Ruby

GOJ
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Less Clutter

• Clean language
• Less noise
• is not needed
• Parenthesis are optional
• Variables dont have type specification
• Last statement of a method returns automatically
• You can even return multiple values!

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Variables

• Dynamic typing
• Output

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Types

• Everything is an object

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Writing a function
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Another function
Returns an array
Assigns elements of array to individual variables
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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 ?

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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 have _at_
• _at_fuel_level
• Class variables use double ats
• _at__at_suggested_pressure
• Global variables use
• ozone

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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
Doesnt modify object
Has side effect mutates object
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Global and Predefined Variables

• This is hideous
• You may be setting some global variable and not
  know it (familiarize yourself)
• Some predefs _, 0, , , !,

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"" vs '' (Double vs. Single Quotes)

• '' is a simple string
• Expressions within "" are evaluated
• Better to use ' if you dont have expressions

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More on Strings