title: Ruby 1.9: What to Expect

h1. Ruby 1.9: What to Expect

Sam Ruby @ OSCON 2008, Portland, Oregon, July 2008

Adapted S6/S9[1] Version from "Original Slide Deck":http://intertwingly.net/slides/2008/oscon/ruby19/1

<hr>
fn1. ("Source":http://slideshow.rubyforge.org/svn/samples/ruby19.textile)

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h1. About Sam Ruby

* Agile Web Development with Rails (3rd Edition)
* Apache Software Foundation
* Atom / Feed Validator
* ECMA .NET CLI (No longer active)
* PHP Group (No longer active)
* RESTful Web Services

==-== "intertwingly.net":http://intertwingly.net


h1. Agenda

* Part 0: Overview
* Part 1: What's Changed?
* Part 2: What's New?



h1. What is Ruby?

* MRI (Matz' Ruby Interpreter)
* Rubinius — RubySpec
* JRuby
* IronRuby
* Ruby.NET
* MacRuby
* MagLev
* YARV (Yet Another Ruby Virtual-machine)

h1. Ruby 1.9 - Major Features

* Performance
* Threads/Fibers
* Encoding/Unicode
* gems is (mostly) built-in now
** No contribs

h1. One Lesson

If you can only take away one message from this presentation:

* @if@ statements do not introduce scope in Ruby.

h1. Replace Methods

Bilingual Ruby

{{{
class Employee
  if String.method_defined?(:encode)
    def name
      ...
    end
  else
    def name
      ...
    end
  end
end
}}}

h1. Replace Implementation

Bilingual Ruby

{{{
if String.method_defined?(:encode)
  module Builder
    ...
  end
else
  class String
    ...
  end
end
}}}

h1. Continuous Integration (CI) Efforts

* Ruby
* Bacon
* Builder
* html5lib
* libxml2
* OpenID
* REXML
* Rake (contrib)
* XMPP4R

h1. Part 1 - What's Changed?

* Single Character Strings
* String Index
* {"a","b"} No Longer Supported
* @Array.to_s@ Now Contains Punctuation
* Colon No Longer Valid In When Statements
* Block Variables Now Shadow Local Variables
* @Hash.index@ Deprecated
* @Fixnum.to_sym@ Now Gone
* Hash Keys Now Unordered
* Stricter Unicode Regular Expressions
* @tr@ and @Regexp@ Now Understand Unicode
* @pack@ and @unpack@
* @BasicObject@ More Brutal Than @BlankSlate@
* Delegation Changes
* Use of $KCODE Produces Warnings
* @instance_methods@ Now an Array of Symbols
* Source File Encoding


h1. Single Character Strings

Ruby 1.9

{{{
irb(main):001:0> ?c
=> "c"
}}}

Ruby 1.8.6

{{{
irb(main):001:0> ?c
=> 99
}}}


h1. String Index

Ruby 1.9

{{{
irb(main):001:0> "cat"[1]
=> "a"
}}}

Ruby 1.8.6

{{{
irb(main):001:0> "cat"[1]
=> 97
}}}


h1. {"a","b"} No Longer Supported

Ruby 1.9

{{{
irb(main):002:0> {1,2}
SyntaxError: (irb):2: syntax error, unexpected ',', expecting tASSOC
}}}

Ruby 1.8.6

{{{
irb(main):001:0> {1,2}
=> {1=>2}
}}}

*Action*: Convert to @{1 => 2}@


h1. @Array.to_s@ Now Contains Punctuation

Ruby 1.9

{{{
irb(main):001:0> [1,2,3].to_s
=> "[1, 2, 3]"
}}}

Ruby 1.8.6

{{{
irb(main):001:0> [1,2,3].to_s
=> "123"
}}}

*Action*: Use @.join@ instead


h1. Colon No Longer Valid In When Statements

Ruby 1.9

{{{
irb(main):001:0> case 'a'; when /\w/: puts 'word'; end
SyntaxError: (irb):1: syntax error, unexpected ':',
expecting keyword_then or ',' or ';' or '\n'
}}}

Ruby 1.8.6

{{{
irb(main):001:0> case 'a'; when /\w/: puts 'word'; end
word
}}}

*Action*: Use semicolon, @then@, or newline


h1. Block Variables Now Shadow Local Variables

Ruby 1.9

{{{
irb(main):001:0> i=0; [1,2,3].each {|i|}; i
=> 0
irb(main):002:0> i=0; for i in [1,2,3]; end; i
=> 3
}}}

Ruby 1.8.6

{{{
irb(main):001:0> i=0; [1,2,3].each {|i|}; i
=> 3
}}}


h1. @Hash.index@ Deprecated

Ruby 1.9

{{{
irb(main):001:0> {1=>2}.index(2)
(irb):18: warning: Hash#index is deprecated; use Hash#key
=> 1
irb(main):002:0> {1=>2}.key(2)
=> 1
}}}

Ruby 1.8.6

{{{
irb(main):001:0> {1=>2}.index(2)
=> 1
}}}

*Action*: Use @Hash.key@


h1. @Fixnum.to_sym@ Now Gone

Ruby 1.9

{{{
irb(main):001:0> 5.to_sym
NoMethodError: undefined method 'to_sym' for 5:Fixnum
}}}

Ruby 1.8.6

{{{
irb(main):001:0> 5.to_sym
=> nil
}}}

h1. @Fixnum.to_sym@ Now Gone (Cont'd)

Ruby 1.9

{{{
# Find an argument value by name or index.
def [](index)
  lookup(index.to_sym)
end
}}}

"@svn.ruby-lang.org/repos/ruby/trunk/lib/rake.rb@":http://svn.ruby-lang.org/repos/ruby/trunk/lib/rake.rb


h1. Hash Keys Now Unordered

Ruby 1.9

{{{
irb(main):001:0> {:a=>"a", :c=>"c", :b=>"b"}
=> {:a=>"a", :c=>"c", :b=>"b"}
}}}

Ruby 1.8.6

{{{
irb(main):001:0> {:a=>"a", :c=>"c", :b=>"b"}
=> {:a=>"a", :b=>"b", :c=>"c"}
}}}

Order is insertion order


h1. Stricter Unicode Regular Expressions

Ruby 1.9

{{{
irb(main):001:0> /\x80/u
SyntaxError: (irb):2: invalid multibyte escape: /\x80/
}}}

Ruby 1.8.6

{{{
irb(main):001:0> /\x80/u
=> /\x80/u
}}}

h1. @tr@ and @Regexp@ Now Understand Unicode

Ruby 1.9

{{{
unicode(string).tr(CP1252_DIFFERENCES, UNICODE_EQUIVALENT).
  gsub(INVALID_XML_CHAR, REPLACEMENT_CHAR).
  gsub(XML_PREDEFINED) {|c| PREDEFINED[c.ord]}
}}}

h1. @pack@ and @unpack@

Ruby 1.8.6

{{{
def xchr(escape=true)
  n = XChar::CP1252[self] || self
  case n when *XChar::VALID
    XChar::PREDEFINED[n] or 
      (n>128 ? n.chr : (escape ? "&##{n};" : [n].pack('U*')))
  else
    Builder::XChar::REPLACEMENT_CHAR
  end
end
unpack('U*').map {|n| n.xchr(escape)}.join
}}}

h1. @BasicObject@ More Brutal Than @BlankSlate@

Ruby 1.9

{{{
irb(main):001:0> class C < BasicObject; def f; Math::PI; end; end; C.new.f
NameError: uninitialized constant C::Math
}}}

Ruby 1.8.6

{{{
irb(main):001:0> require 'blankslate'
=> true
irb(main):002:0> class C < BlankSlate; def f; Math::PI; end; end; C.new.f
=> 3.14159265358979
}}}

*Action*: Use @::Math::PI@


h1. Delegation Changes

Ruby 1.9

{{{
irb(main):002:0> class C < SimpleDelegator; end
=> nil
irb(main):003:0> C.new('').class
=> String
}}}

Ruby 1.8.6

{{{
irb(main):002:0> class C < SimpleDelegator; end
=> nil
irb(main):003:0> C.new('').class
=> C
irb(main):004:0>
}}}

"Defect 17700":http://rubyforge.org/tracker/index.php?func=detail&aid=17700&group_id=426&atid=1698


h1. Use of $KCODE Produces Warnings

Ruby 1.9

{{{
irb(main):004:1> $KCODE = 'UTF8'
(irb):4: warning: variable $KCODE is no longer effective; ignored
=> "UTF8"
}}}

Ruby 1.8.6

{{{
irb(main):001:0> $KCODE = 'UTF8'
=> "UTF8"
}}}

h1. @instance_methods@ Now an Array of Symbols

Ruby 1.9

{{{
irb(main):001:0> {}.methods.sort.last
=> :zip
}}}

Ruby 1.8.6

{{{
irb(main):001:0> {}.methods.sort.last
=> "zip"
}}}

*Action*: Replace @instance_methods.include?@ with @method_defined?@


h1. Source File Encoding

Basic

{{{
# coding: utf-8
}}}

Emacs

{{{
# -*- encoding: utf-8 -*-
}}}


Shebang

{{{
#!/usr/local/rubybook/bin/ruby
# encoding: utf-8
}}}

h1. Real Threading

* Race Conditions
* Implicit Ordering Assumptions
* Test Code

h1. Implications

* Changes are straightforward
* Cumulative effect is massive
* The biggest obstacle to Ruby 1.9's adoption is the sheer number of mostly working but essentially unmaintained gems that virtually everybody in the Ruby community depends on
* Emergence of alternate implementations also a source for inertia

h1. Recommendations

Encourage maintainers of gems to:

* Produce versions of gems that work with 1.8.x and 1.9
* For long term, move to distributed version control systems (DVCS) like @git@

h1. Rails Dependencies

@actionmailer-2.1.0@, @actionpack-2.1.0@, @activerecord-2.1.0@, @activeresource-2.1.0@, @activesupport-2.1.0@, @builder-2.1.2@, @memcache-client-1.5.0@, @rails-2.1.0@, @rake-0.8.1@, @sources-0.0.1@, @text-format-0.6.3@, @tmail-1.2.3@, @tzinfo-0.3.8@, @xml-simple-1.0.11@, @html-scanner@, @db2.rb@, @mysql.rb@

h1. Part 2 - What's New?

* Alternate Syntax for Symbol as Hash Keys
* Block Local Variables
* Inject Methods
* @to_enum@
* No block? Enum!
* Lambda Shorthand
* Complex Numbers
* Decimal Is Still Not The Default
* Regex "Properties"
* Splat in Middle
* Fibers
* Break Values
* "Nested" Methods


h1. Alternate Syntax for Symbol as Hash Keys

Ruby 1.9

{{{
{a: b}

redirect_to action: show
}}}

Ruby 1.8.6

{{{
{:a => b}

redirect_to :action => show
}}}


h1. Block Local Variables

Ruby 1.9

{{{
[1,2].each {|value; t| t=value*value}
}}}


h1. Inject Methods

Ruby 1.9

{{{
[1,2].inject(:+)
}}}

Ruby 1.8.6

{{{
[1,2].inject {|a,b| a+b}
}}}


h1. @to_enum@

Ruby 1.9

{{{
short_enum = [1, 2, 3].to_enum
long_enum = ('a'..'z').to_enum
loop do
  puts "#{short_enum.next} #{long_enum.next}"
end
}}}

h1. No block? Enum!

Ruby 1.9

{{{
e = [1,2,3].each
}}}

h1. Lambda Shorthand

Ruby 1.9

{{{
p = -> a,b,c {a+b+c}
puts p.(1,2,3)
puts p[1,2,3]
}}}

Ruby 1.8.6

{{{
p = lambda {|a,b,c| a+b+c}
puts p.call(1,2,3)
}}}

h1. Complex Numbers

Ruby 1.9

{{{
Complex(3,4) == 3 + 4.im
}}}


h1. Decimal Is Still Not The Default

Ruby 1.9

{{{
irb(main):001:0> 1.2-1.1
=> 0.0999999999999999
}}}

h1. Regex "Properties"

Ruby 1.9

{{{
/\p{Space}/
}}}

Ruby 1.8.6

{{{
/[:space:]/
}}}


h1. Splat in Middle

Ruby 1.9

{{{
def foo(first, *middle, last)

(->a, *b, c {p a-c}).(*5.downto(1))
}}}

h1. Fibers

Ruby 1.9

{{{
f = Fiber.new do
  a,b = 0,1
  Fiber.yield a
  Fiber.yield b
  loop do
    a,b = b,a+b
    Fiber.yield b
  end
end
10.times {puts f.resume}
}}}

h1. Break Values

Ruby 1.9

{{{
match =
   while line = gets
     next if line =~ /^#/
     break line if line.find('ruby')
   end
}}}

h1. "Nested" Methods

Ruby 1.9

{{{
def toggle
  def toggle
    "subsequent times"
  end
  "first time"
end
}}}

h1. Questions

* Any questions?
* "Programming Ruby 3":http://www.pragprog.com/titles/ruby3/programming-ruby-3
* Thanks for coming!