let's learn ruby - basic

Let’s Learn Ruby - Basic

Ruby Tuesday

https://www.facebook.com/groups/142197385837507/photo by othree

RubyConf Taiwan

http://rubyconf.tw/

Rails Girls Taipei

https://www.facebook.com/railsgirlstw

WebConf Taiwan 2014

750+ attendees

all tickets sold out in 4 mins

Let’s Learn Ruby

What I want?

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Problem Solving

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Active Ecosystem

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Scenario

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open source projects on Github

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History

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まつもと ゆきひろ (Matz)

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first released at 1995

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2.0 released at 2013

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2.1 released at 2013.12

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Why Ruby? free, open source, easy to learn

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Ruby != Rails

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Happy, and Fun

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Rubies CRuby(MRI), REE, mRuby, MacRuby,

JRuby, IronRuby, Rubinius..etc

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Version 1.8, 1.9, 2.0, 2.1

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Ruby 1.8 has no future

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RVM Ruby Version Manager

https://rvm.io/

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Editors Vim, Emacs, Sublime Text... etc

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coding style

https://github.com/styleguide/ruby

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But Ruby is Slow..?

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What can Ruby do?

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Rake Make, but Ruby version.

Rack http://rake.rubyforge.org/

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Rack it’s a specification (and implementation) of a minimal abstract Ruby API that models HTTP. such as Sinatra, Ruby on Rails

Rack http://rack.rubyforge.org/Sinatra http://www.sinatrarb.comRuby on Rails http://rubyonrails.org/

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developing MacOS and iOS app

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drawing, image processing, music..

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Install Ruby now!

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http://tryruby.org

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Interactive Ruby, irb

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Gem

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gem install PACKAGE_NAME

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gem env

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gem list

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Variables and Constants

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local variable variable

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global variable $variable

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instance variable @variable

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class variable @@variable

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virtual variable true, false, self, nil

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variable assignment a = 1

x, y, z = 1, 2, 3

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Constant begins with a capital letter,

and it can be changed

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Reserved word and Keyword

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Reserved word and Keyword

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Logic and Flow Control

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only false and nil are false

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true v.s TrueClass false v.s FalseClass

nil v.s NilClass

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if..elsif..end

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unless = not if

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if modifier

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case .. when..

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BEGIN{} and END{}

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a = true ? 'a' : 'b'

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a ||= 'a'

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Comment # single line

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Comment =begin .. =end

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Loop and Iteration

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for.. in..

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while .. end

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until .. end

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until = not while

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times

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upto, downto

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each, each_with_index

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Integer

http://www.ruby-doc.org/core-2.1.0/Integer.html

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Fixnum and Bignum

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10 / 3

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String

http://ruby-doc.org/core-2.1.0/String.html

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single and double quotes

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%q v.s %Q

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"%s" % "eddie"

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string interpolation

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Exercise please calculate how many “characters” and “words” of a section of a random article with Ruby.

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Exercise please convert string “abcdefg” to “gfedcba” without using String#reverse method.

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Array

http://ruby-doc.org/core-2.1.0/Array.html

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Array.new v.s []

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%w

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Exercise please sort a given array [1, 3, 4, 1, 7, nil, 7], and remove nil and duplicate number.

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Exercise please covert a given array [1, 2, 3, 4, 5] to [1, 3, 5, 7, 9] with Array#map method.

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Exercise please draw 5 unique random number between 1 to 52.

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Hash

http://ruby-doc.org/core-2.1.0/Hash.html

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Hash.new v.s {}

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a = { :name => 'eddie' } a = { name: 'eddie' }

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Range

http://ruby-doc.org/core-2.1.0/Range.html

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(1..10) v.s (1...10)

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Exercise please calculate the sum from 1 to 100 with Range.

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Methods

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def method_name(param) ... end

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parentheses can be omitted

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? and !

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return value

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Singleton Method

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class Cat def walk puts "I'm walking" end end ! cat = Cat.new def cat.fly puts "I can fly" end cat.fly

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Method Missing

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def method_missing(method_name) puts "method: #{method_name} is called!" end !

something_not_exists()

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Exception Handling begin .. rescue.. else.. ensure.. end

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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

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Block

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Proc

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my_square = Proc.new { | x | x ** 2 } !# how to call a proc puts my_square.call(10) # 100 puts my_square[10] # 100 puts my_square.(10) # 100 puts my_square === 10 # 100

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lambda, ->

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my_lambda = lambda { | x | x ** 2 } !# new style in 1.9 my_lambda = -> x { x ** 2 } !# how to call a lambda? puts my_lambda.call(10) # 100 puts my_lambda[10] # 100 puts my_lambda.(10) # 100 puts my_lambda === 10 # 100

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Proc v.s lambda

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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

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{} v.s do..end

http://blog.eddie.com.tw/2011/06/03/do-end-vs-braces/

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Yield

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Object-Oriented Programming

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everything in Ruby is an Object

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object = state+ behavior

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root class = Object root class would be BasicObject in Ruby 1.9

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class ClassName < ParentClass ... end

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Naming Convention

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initialize

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ClassName.new

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self = current object

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instance and class variable

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instance and class method

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Exercise please create a Dog class and Cat class, which are both inherited from Animal class, and implement “walk” and “eat” methods.

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public, protected and private method

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getter and setter

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attr_reader, attr_writer and attr_accessor

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Open Class

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Module

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module ModuleName ... end

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module has no inheritance

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module has no instance

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Naming Convention

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require v.s load

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Priority?

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Exercise please create a Bird class, which is also inherited from Animal class, but include a Fly module.

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Mixin

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Ruby is single inheritance

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Duck Typing

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include v.s extend

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Bundle

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Gemfile

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http://rubygems.org/

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gem "nokogiri", :git => "git://github.com/tenderlove/nokogiri.git" gem "secret_gem", :path => "~/my_secret_path"

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bundle install

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pack your own gem!

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1. bundle gem NEW_NAME 2. gem build NEW_NAME.gemspec 3. gem push NEW_NAME.gem

http://guides.rubygems.org/make-your-own-gem/

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Exercise please try to create a Gem spec with bundle command, modify, build and push to rubygems.org.

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Rake

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desc "mail sender" task :sendmail do puts "grap mailing list from database..." sleep 3 puts "mail sending..." sleep 3 puts "done!" end

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task :goto_toliet do puts "goto toliet" end ! task :open_the_door => :goto_toliet do puts "open door" end

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TDD

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require “minitest/autorun" !class TestMyBMI < MiniTest::Unit::TestCase def test_my_calc_bmi_is_ok assert_equal calc_bmi(175, 80), 26.12 end end !def calc_bmi(height, weight) bmi = ( weight / (height/100.0) ** 2 ).round(2) end

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require "minitest/autorun" describe "test my bmi calculator" do it "should calc the correct bmi" do calc_bmi(175, 80).must_equal 26.12 end end def calc_bmi(height, weight) bmi = ( weight / (height/100.0) ** 2 ).round(2) end

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Ruby Koans

http://rubykoans.com/

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Ruby Object Model

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At last..

photo by redjar

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pick up one scripting language

photo by Quality & Style

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@eddiekao

https://www.ruby-lang.org/zh_tw/

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Ruby is fun!

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The only limitation is your imagination.

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