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Ruby for Starter
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高見龍
March 23, 2013
Programming
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Ruby for Starter
高見龍
March 23, 2013
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Transcript
Ruby Starter eddie@fju
None
current status
80% iOS app, 20% Ruby/Rails
What I want?
Problem Solving
History
まつもと ゆきひろ (Matz)
first released at 1995
2.0 released at 2013
None
Why Ruby? free, open source, easy to learn
Ruby != Rails
Happy, and Fun
Rubies CRuby(MRI), REE, mRuby, JRuby, IronRuby, Rubinius..etc
Version 1.8, 1.9, 2.0
Ruby 1.8 has no future
RVM Ruby Version Manager https://rvm.io/
Editors Vim, Emacs, TextMate, Sublime Text... etc
git
coding style https://github.com/styleguide/ruby
Variables and Constants
local variable variable
global variable $variable
instance variable @variable
class variable @@variable
virtual variable true, false, self, nil
variable assignment a = 1 x, y, z = 1,
2, 3
Constant begins with a capital letter, and it can be
changed
Reserved word and Keyword
Logic and Flow Control
only false and nil are false
true v.s. TrueClass false v.s. FalseClass nil v.s. NilClass
if..elsif..end
unless = if not
if modifier
case .. when..
BEGIN{} and END{}
a = true ? 'a' : 'b'
a ||= 'a'
Comment # single line
Comment =begin .. =end
Loop and Iteration
for.. in..
while .. end
until .. end
until = while not
times
upto, downto
each, each_with_index
Block
Proc
my_square = Proc.new { | x | x ** 2
} my_square.call(10) # 100 my_square[10] # 100
lambda, ->
my_lambda = lambda { | x | x ** 2
} # new style in 1.9 my_lambda = -> x { x ** 2 } # how to call a lambda? my_lambda.call(10) my_lambda[10]
Proc v.s. lambda
def proc_test puts "hello" my_proc = Proc.new { return 1
} my_proc.call puts "ruby" end def lambda_test puts "hello" my_lambda = lambda { return 1 } my_lambda.call puts "ruby" end
{} v.s. do..end http://blog.eddie.com.tw/2011/06/03/do-end-vs-braces/
Number
Fixnum and Bignum
10 / 3
String http://ruby-doc.org/core-1.9.2/String.html
single and double quotes
%q v.s. %Q
"%s" % "eddie"
string interpolation
Array http://ruby-doc.org/core-1.9.2/Array.html
Array.new v.s. []
%w
Hash http://ruby-doc.org/core-1.9.2/Hash.html
Hash.new v.s {}
a = { :name => 'eddie' } a = {
name: 'eddie' }
Range http://ruby-doc.org/core-1.9.2/Range.html
(1..10) v.s. (1...10)
Methods
def method_name(param) ... end
parentheses can be omitted
? and !
return value
Singleton Method
class Cat def walk puts "I'm walking" end end cat
= Cat.new def cat.fly puts "I can fly" end cat.fly
Method Missing
def method_missing(method_name) puts "method: #{method_name} is called!" end [1, 2,
3, 4].hello
Exception Handling begin .. rescue.. else.. ensure.. end
def open_my_file(file_name) File.open file_name do |f| puts f.read end end
begin open_my_file("block_demo.r") rescue => e puts e else puts "it's working good!" ensure puts "this must be executed, no matter what" end
Object-Oriented Programming
everything in Ruby is an Object
object = state+ behavior
top class = Object top class would be BasicObject in
Ruby 1.9
class ClassName < ParentClass ... end
Naming Convention
initialize
ClassName.new
self = current object
instance and class variable
instance and class method
public, protected and private method
getter and setter
attr_reader, attr_writer and attr_accessor
Open Class
Module
module ModuleName ... end
module has no inheritance
module has no instance
Naming Convention
require v.s. load
Mixin
Ruby is single inheritance
Duck Typing
include v.s. extend
Gem
gem install PACKAGE_NAME
gem env
Bundle
Gemfile
gem "nokogiri", :git => "git://github.com/tenderlove/nokogiri.git" gem "secret_gem", :path => "~/my_secret_path"
bundle install
pack your own gem!
1. bundle gem NEW_NAME 2. gem build NEW_NAME.gemspec 3. gem
push NEW_NAME.gem http://docs.rubygems.org/read/chapter/20
Rake
Ruby Object Model