intro for ror
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Introduction For Ruby On RailsTRANSCRIPT
An Introduction to Ruby and Rails
Matthew BohnsackWannabe RubyistNovember 9th 2005
November 9th 2005 2An Introduction to Ruby and Rails
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
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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 4An 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.
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Must have tool #1: irb
Interactive ruby console:Experiment on the flyTab complete object methods…
# ~/.irbrc
require 'irb/completion'
use_readline=true
auto_indent_mode=true
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Must have tool #2: ri
Console-based Ruby doc tool
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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…
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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 9An Introduction to Ruby and Rails
Ruby in a nutshell – objects have methods
Bang on the tab key in irb to see the methods that are available for each object.
November 9th 2005 10An Introduction to Ruby and Rails
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
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Ruby in a nutshell – Arrays
November 9th 2005 12An Introduction to Ruby and Rails
Ruby in a nutshell – Hashes
November 9th 2005 13An 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 14An Introduction to Ruby and Rails
Ruby in a nutshell – Blocks & Iterators
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Ruby in a nutshell – It’s easy to build classes
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Ruby in a nutshell – It’s fun to play with classes (like the one we just made)
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Ruby in a nutshell – Classes are open
Example shown here uses our Hacker class, but what happens when the whole language is open?
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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.
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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
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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’
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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
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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
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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
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The End / Questions