Intro To Ror

An Introduction to Ruby and Rails Matthew Bohnsack Wannabe Rubyist November 9 th 2005

Outline What is Ruby and why should I care? What is Rails and why should I care? Two must-have tools for Ruby development Major Ruby features (the language in a nutshell) Rails overview Where to go for more information Questions / Hacking November 9th 2005 An Introduction to Ruby and Rails

What is Ruby? Why should I care? What: The Wikipedia answer is here . Created/lead by Matz (Japanese) Open Source interpreted scripting language, like Perl, Python, Tcl, etc., but focused on being very object oriented, expressive, and bringing joy to programming . Principle of least surprise Why: Productivity ideas presented in Ousterhout’s 1998 paper coming to very serious critical mass (and beyond) Learn a new language to learn new ways of thinking about code in any language (e.g., blocks and iterators) Joy! November 9th 2005 An Introduction to Ruby and Rails

What is Rails? Why should I care? What: Web Framework that makes building database-driven MVC-oriented web apps easy through a template engine, ORM ( ActiveRecord ) and other best practices, such as test driven development, deployment tools, patterns, etc. Much less complicated than J2EE solutions, but perhaps more so than PHP or Perl in cgi-bin. Copy cats are being created in other languages: Python (TurboGears) Perl (Maypole) http://rubyonrails.org/ + book + online screencasts + online docs & tutorials Why: I’ve been watching the world of web development since ~ 1995, and I’ve never seen anything like Rails in terms of buzz, momentum, adoption rate, etc. November 9th 2005 An Introduction to Ruby and Rails

Must have tool #1: irb Interactive ruby console : Experiment on the fly Tab complete object methods … November 9th 2005 An Introduction to Ruby and Rails # ~/.irbrc require 'irb/completion ' use_readline=true auto_indent_mode=true

Must have tool #2: ri Console-based Ruby doc tool November 9th 2005 An Introduction to Ruby and Rails

Ruby in a nutshell – irb sessions follow Like all interpreted scripting languages, you can put code into a file, chmod +x, then just execute it. But, we’ll mostly use irb sessions in this presentation… November 9th 2005 An Introduction to Ruby and Rails

Ruby in a nutshell – objects are everywhere Some languages have built-in types that aren’t objects. Not so with Ruby. Everything’s an object: November 9th 2005 An Introduction to Ruby and Rails

Ruby in a nutshell – objects have methods November 9th 2005 An Introduction to Ruby and Rails Bang on the tab key in irb to see the methods that are available for each object.

Ruby in a nutshell – Variables Local variables - start with lower case: foo bar Global variables - start with dollar sign: $foo $bar Constants and Classes – start with capital letter: CONSTANT Class Instance variables – start with at sign: @foo @bar Class variables – start with double at sign: @@foo @@bar November 9th 2005 An Introduction to Ruby and Rails

Ruby in a nutshell – Arrays November 9th 2005 An Introduction to Ruby and Rails

Ruby in a nutshell – Hashes November 9th 2005 An Introduction to Ruby and Rails

Ruby in a nutshell – Symbols Starts with a ‘:’ Only one copy of a symbol kept in memory November 9th 2005 An Introduction to Ruby and Rails

Ruby in a nutshell – Blocks & Iterators November 9th 2005 An Introduction to Ruby and Rails

Ruby in a nutshell – It’s easy to build classes November 9th 2005 An Introduction to Ruby and Rails

Ruby in a nutshell – It’s fun to play with classes (like the one we just made) November 9th 2005 An Introduction to Ruby and Rails

Ruby in a nutshell – Classes are open Example shown here uses our Hacker class, but what happens when the whole language is open? November 9th 2005 An Introduction to Ruby and Rails

Ruby in a nutshell – Other notes on Classes Ruby only has single inheritance. This makes things simpler, but mix-ins provide much of multiple inheritance’s benefit, without the hassle. November 9th 2005 An Introduction to Ruby and Rails

Ruby in a nutshell – a few gotchas Despite the principle of least surprise: Zero isn’t false: No increment operator ( foo++ ). Instead use: foo += 1 foo = foo + 1 November 9th 2005 An Introduction to Ruby and Rails

Ruby in a nutshell – RubyGems CPAN for Ruby? http://docs.rubygems.org/ Examples: gem list gem install redcloth --version ">= 3.0.0" … Using gems in your program: require ‘rubygems’ require ‘some_gem’ November 9th 2005 An Introduction to Ruby and Rails

Want to learn more Ruby? Excellent, simple, beginner’s tutorial: http://www.math.umd.edu/~dcarrera/ruby/0.3/index.html Other stuff at end of talk Start hacking November 9th 2005 An Introduction to Ruby and Rails

Quick Rails Demo – Build a TODO list application in 5 minutes Define database rails todo cd todo Edit config/database.yml ./script/generate model Todo ./script/generate scaffold todo Look at scaffolding ./script/server –b www.bohnsack.com Add due_date field, regenerate scaffolding, and check the results ./script/console November 9th 2005 An Introduction to Ruby and Rails

Where to go for more information Books: Online material: First edition of Pickaxe online for free http://www.ruby-doc.org/ why’s (poignant) guide to Ruby http://rubyonrails.org/ Rails screencast (s) Planet Ruby on Rails November 9th 2005 An Introduction to Ruby and Rails

The End / Questions November 9th 2005 An Introduction to Ruby and Rails

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