What's new in ruby Since 2.0.0

A short overview of new and changed things in Ruby since 2.0.0 given at the October 2014 Ruby Ireland meetup.

Source: https://github.com/chrismcg/presentations/blob/master/whats_new_in_ruby_since_200/whats_new_in_ruby_since_200.md

Best viewed with Deckset App

Transcript

1. What's'new'in'Ruby'since'2.0.0 Chris&McGrath @chrismcg 1
2. Speed 2
3. Garbage'Collector 3
4. Mark%and%Sweep%in%Ruby%1.8 • Stop&everything&Ruby&is&doing • Go&through&and&mark&all&objects&that&have&a&reference&to&them • Sweep&all&the&objects&that&aren’t&marked 4
5. 1.8 (Images(from(Aman(Gupta's(blog) 5
6. 1.9.3 Ruby%1.9.3%made%the%sweep%phase%"lazy"%so%the%pause%is%just%the% mark%phase (Images(from(Aman(Gupta's(blog) 6
7. Ruby%2.0 Copy%On%Write (Images(from(Aman(Gupta's(blog) 7
8. Ruby%2.1 Genera&onal)GC (Images(from(Aman(Gupta's(blog) 8
9. Ruby%2.2 Symbols Incremental*GC 9
10. GC#Tuning 10
11. Refinements • Extend(classes((monkeypatch)(locally(instead(of(globally • Introduced(as(experimental(in(2.0 • Reduced(in(scope(and(complexity(since(ini@al(idea • Not(experimental(in(2.1 11
12. Refinements module Stats refine Array do def mean inject(0) { |sum, x| sum + x } / size end end end 12
13. Refinements a1 = [1, 2, 3, 4] a1.mean rescue "no mean method" # => "no mean method" using Stats a2 = [2, 4, 6, 8] a2.mean # => 5 a1.mean # => 2 13
14. Refinements class Analyzer using Stats def initialize(array) @array = array end def summary { mean: @array.mean } end end 14
15. Refinements a1 = [1, 2, 3, 4] analyzer = Analyzer.new(a1) a1.mean rescue "no mean method" # => "no mean method" analyzer.summary # => {:mean=>2} 15
16. Refinements()(Lexically(scoped • using"to"end"of"file • using"to"end"of"module • using"to"end"of"string"being"evaled • Don't"apply"when"re:opening"classes 16
17. Refinements class Analyzer def short_summary { m: @array.mean } end end a1 = [1, 2, 3, 4] analyzer = Analyzer.new(a1) analyzer.summary # => {:mean=>2} analyzer.short_summary rescue "no mean method" # => "no mean method" 17
18. Refinements • Seem%like%a%great%fit%for%gem%authors • Not%in%JRuby%yet%(but%coming) • Not%in%Rubinius • What%should%something%like%Ac?veSupport%do? • Haven't%seen%any%benchmarks%yet%(but%not%expec?ng%them%to%be% slow) 18
19. Keyword(Arguments • Introduced+in+Ruby+2.0 • Improved+in+2.1 • Backwards+compa<ble+with+hash+syntax • Be@er+error+messages+for+missing+/+wrong+arguments 19
20. "Fake"&Keyword&Arguments&in&Ruby&1.8/1.9 def render(content, opts = {}) width = opts[:width] height = opts[:height] ... end render "* foo" 20
21. Need$some$defaults def render(content, opts = {}) width = opts[:width] || 1920 height = opts[:height] || 1080 ... end render "* foo" 21
22. :full%means%use%width%or%height%of%page def render(content, opts = {}) width = opts.fetch(:width) { 1920 } width = @page.width if width == :full height = opts.fetch(:height) { 1080 } height = @page.height if height == :full ... end render "* foo", :width => :full render "* bar", :hieght => 786 # doesn't pick up on typo 22
23. With%Ruby%2.x%keyword%arguments def render(content, width: 1920, height: 1080) width = @page.width if width == :full height = @page.height if height == :full ... end render "* foo" render "* bar", hieght: 786 # => # ~> -:7:in `<main>': unknown keyword: hieght (ArgumentError) 23
24. If#the#user#must#specify#width def render(content, width:, height: 1080) width = @page.width if width == :full height = @page.height if height == :full end render "* foo" # ~> -:6:in `<main>': missing keyword: width (ArgumentError) 24
25. Benefits • Be$er&errors&and&programmer&doesn't&have&to&manually&check& arguments • Easier&to&add&named&arguments&to&those&methods&you&pass&four& numbers&into • Named&arguments&mean&you&can&change&argument&posi=on& without&needing&to&refactor • Named&arguments&make&it&clear&where&method&call&is&what&the& arguments&are 25
26. Drawbacks • More&typing&if&you're&making&lots&of&calls&with&named&arguments • ... (Check'out'RubyTapas'episodes'186'and'187'to'learn'how'to' handle'extra'arguments'with'the'**'operator'and'just'how'flexible' they'are.) 26
27. Module#prepend+(❤) • include"puts"module"a-er"current"class"in"method"lookup" chain • prepend"puts"it"before • Removes"need"for"alias_method_chain,"breaking"super"etc. 27
28. Module#include+/+prepend module Stats def mean puts "Stats#mean" super rescue puts "Stats#mean no superclass mean method" end end 28
29. Module#include+/+prepend class Analyzer include Stats def mean puts "Analyzer#mean" super end end Analyzer.ancestors # => [Analyzer, Stats, Object, Kernel, BasicObject] Analyzer.new.mean # => nil # >> Analyzer#mean # >> Stats#mean # >> Stats#mean no superclass mean method 29
30. Module#include+/+prepend class Analyzer2 prepend Stats def mean puts "Analyzer2#mean" super rescue puts "Analyzer2#mean no superclass mean method" end end Analyzer2.ancestors # => [Stats, Analyzer2, Object, Kernel, BasicObject] Analyzer2.new.mean # => nil # >> Stats#mean # >> Analyzer2#mean # >> Analyzer2#mean no superclass mean method 30
31. Cache&decorator class Analyzer def expensive_method puts "thinking really hard!" # do lots of calculations 42 end end 31
32. Cache&decorator module AnalyzerCacher def expensive_method @expensive_method_result ||= super end end class Analyzer prepend AnalyzerCacher end 32
33. Cache&decorator a = Analyzer.new a.expensive_method # => 42 # >> thinking really hard! a.expensive_method # => 42 a.expensive_method # => 42 (This&could&of&course&be&generalized&with&meta&programming) 33
34. Method'Cache • Pre%Ruby%2.1%any%change%to%any%class%would%clear%all%the%method% caches • Performance%hit,%especially%if%you're%doing%something%like%DCI • Post%Ruby%2.1%just%the%cache%for%the%class%and%it's%subclasses%is% changed • Can%use%Busted%tool%to%see%where%cache%is%busted%on%2.1+ 34
35. Other&op)miza)ons • Kernel#require+op.mized+to+make+rails+loading+fast • Backtrace+genera.on+op.mized • Hash#shi<+performance+increased,+so+along+with+preserving+ inser.on+order+can+make+a+nice+li@le+LRU+Cache+with+it 35
36. __dir__ (instead)of)File.dirname(__FILE__)) require __dir__ + '/foo' File.read(__dir__ + '/.config') (note&lower&case) 36
37. %i#and#%I Create&arrays&of&symbols [1] pry(main)> n = 10 => 10 [2] pry(main)> %i(foo bar#{n}) => [:foo, :"bar\#{n}"] [3] pry(main)> %I(foo bar#{n}) => [:foo, :bar10] 37
38. def$returns$method$name$as$symbol (Ruby&2.1+) method = def foo puts "bar" end method # => :foo 38
39. def$returns$method$name$as$symbol (Ruby&2.1+) Handy&for&metaprogramming&and&just&making&one&method&private private def foo #... end 39
40. Excep&on#cause-(2.1) class Downloader class DownloadException < StandardError; end def download! begin raise "boom!" rescue RuntimeError raise DownloadException end end end 40
41. Excep&on#cause-(2.1) begin Downloader.new.download! rescue => e e.to_s # => "Downloader::DownloadException" e.cause # => #<RuntimeError: boom!> end 41
42. Lazy%enumerators #lazy!can!be!called!on!any!enumerable.!Can!do!FP!style!stuff!like: [25] pry(main)> [1, 2, 3, 4].lazy.cycle.take(20) => #<Enumerator::Lazy: ...> [26] pry(main)> [1, 2, 3, 4].lazy.cycle.take(20).to_a => [1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4] 42
43. Lazy%enumerators Find%first%three%four%le0er%words%in%/usr/share/dict/words% without%loading%whole%file%into%memory: File.open('/usr/share/dict/words').lazy. map(&:chomp). select { |w| w.length == 4 }. take(3). force => ["Aani", "Aaru", "abac"] 43
44. Module.const_get Knows&about&namespaces&since&2.0 module Foo class Bar end end Object.const_get("Foo::Bar") # => Foo::Bar 44
45. Kernel#itself+(2.2) [1, 2, 3, 4, 1, 5, 2, 3, 5, 6].group_by(&:itself) => {1=>[1, 1], 2=>[2, 2], 3=>[3, 3], 4=>[4], 5=>[5, 5], 6=>[6]} (This&is&my&favourite&new&method&name) 45
46. warn%accepts%mul.ple%arguments (warn&==&puts&for&stderr) pry(main)> warn "warning 1", "warning 2" warning 1 warning 2 46
47. Thread'and'Fibre'stack'sizes • Fibre'stack'size'hardcoded'at'4K'in'1.9.x • Now'se:able'via'ENV'variable'in'2.x 47
48. Thread'and'Fibre'stack'sizes • RUBY_THREAD_VM_STACK_SIZE:4vm4stack4size4used4at4thread4 creaCon.4default:4128KB4(32bit4CPU)4or4256KB4(64bit4CPU). • RUBY_THREAD_MACHINE_STACK_SIZE:4machine4stack4size4 used4at4thread4creaCon.4default:4512KB4or41024KB. • RUBY_FIBER_VM_STACK_SIZE:4vm4stack4size4used4at4fiber4 creaCon.4default:464KB4or4128KB. • RUBY_FIBER_MACHINE_STACK_SIZE:4machine4stack4size4used4 at4fiber4creaCon.4default:4256KB4or4256KB. 48
49. Thanks!! • Ruby&2.0&NEWS • Ruby&2.1&NEWS • Ruby&2.2&(trunk)&NEWS • Ruby&2.0.0&in&detail • Ruby&2.1&in&detail • Ruby&2&Keyword&Arguments 49
50. More%links • Ruby&2.1&Garbage&Collec3on:&ready&for&produc3on • Demys3fying&the&Ruby&GC • Visualizing&Garbage&Collec3on&in&Ruby&and&Python • Introducing&Incremental&GC&algorithm • Ruby&2.1:&OutDofDBand&GC • MRI's&Method&Caches 50