1. Ruby 2.1
Benjamin Tan Wei Hao (@bentanweihao)!

4. What's New?!
1.
!
2.
3.
4.
5.
6.
Rational Number & Complex
Number Literals !
def‘s return value!
Refinements!
Required Keyword Arguments!
Garbage Collector!
Object Allocation Tracing!

5. BUT FIRST!

6. Getting
Ruby 2.1

7. RVM!
$ rvm get head!
$ rvm install ruby-2.1.0!
$ rvm use ruby-2.1.0!

8. RBENV!
$ rbenv install 2.1.0!
$ rbenv rehash!
$ rbenv global 2.1.0!

9. what's
new?

10. What's New?!
1.
!
2.
3.
4.
5.
6.
Rational Number & Complex
Number Literals !
def‘s return value!
Refinements!
Required Keyword Arguments!
Garbage Collector!
Object Allocation Tracing!

11. Complex/
Rational
Literals

12. Complex Literals!
< Ruby 2.1
> Complex(2, 3)!
=> (2+3i)!

13. Complex Literals!
< Ruby 2.1
> Complex(2, 3)!
=> (2+3i)!
Ruby 2.1
> (2 + 3i)!
=> (2+3i)!
> (2 + 3i) + Complex(5, 4i)!
=> (3+3i)!

14. Rational Literals!
> 2/3.0 + 5/4.0!
=> 1.91666666666665!
< Ruby 2.1

15. Rational Literals!
> 2/3.0 + 5/4.0!
=> 1.91666666666665!
< Ruby 2.1
Ruby 2.1
> 2/3r + 5/4r!
=> (23/12)!

16. def's
return
value

17. def's return value!
< Ruby 2.1
> def foo; end!
=> nil!

18. def's return value!
< Ruby 2.1
> def foo; end!
=> nil!
Ruby 2.1
> def foo; end!
=> :foo!

19. def's return value!
module Foo!
def public_method!
end!
!
private # <- this sucks!
def a_private_method!
end!
end!

21. def's return value!
module Foo!
def public_method!
end!
!
private def some_other_method!
end!
!
private def a_private_method!
end!
end!
!
Foo.private_instance_methods!
=> [:some_other_method, :a_private_method]!

22. def's return value!
module Foo!
def public_method!
end!
!
private def some_other_method!
end!
!
private def a_private_method!
end!
end!
!
Foo.private_instance_methods!
=> [:some_other_method, :a_private_method]!

23. Refinements

24. Refinements
are no longer experimental.!

25. Refinements!
class String!
def count!
Float::INFINITY!
end!
end!

26. Refinements
let's us scope our modifications!

27. Defining a Refinement!
module Permalinker!
refine String do!
def permalinkify!
downcase.split.join("-")!
end!
end!
end!
!

28. Using a Refinement!
class Post!
->using Permalinker!
module Permalinker!
!
refine String do!
def permalinkify!
def initialize(title)!
downcase.split.join("-")!
@title = title!
end!
end!
end!
end!
!
!
def permalink!
@title.permalinkify!
end!
end!

29. Using a Refinement!
class Post!
using Permalinker!
module Permalinker!
!
refine String do!
def permalinkify!
def initialize(title)!
downcase.split.join("-")!
@title = title!
end!
end!
end!
end!
!
!
def permalink!
->@title.permalinkify!
end!
end!

30. Required
Keyword ArGS

31. Required Keyword Args!
< Ruby 2.1
def permalinkfiy(str, delimiter: "-")!
str.downcase.split.join(delimiter)!
end!
Question: How do we make str
required?!

32. Required Keyword Args!
Ruby 2.1
def permalinkfiy(str:, delimiter: "-")!
str.downcase.split.join(delimiter)!
end!

33. Required Keyword Args!
> permalinkify(delimiter: "-lol-")!
ArgumentError: missing keyword: str!
from (irb):49!
from /usr/local/var/rbenv/
versions/2.1.0/bin/irb:11:in `<main>'!

34. RGengc
Restricted Generational Garbage
Collector!

35. Ruby 1.8: Simple M&S!
Credits: http://tmm1.net/ruby21-rgengc/!

36. Ruby 1.9.3: Lazy Sweep!
Credits: http://tmm1.net/ruby21-rgengc/!

37. Ruby 2.0: Bitmap for COW-Safety!
Credits: http://tmm1.net/ruby21-rgengc/!

38. Ruby 2.1: RGenGC!
Credits: http://tmm1.net/ruby21-rgengc/!

39. Generational GC!
Key Idea:!
!
Objects that are most
recently created often
die young.!

40. Generational GC!
• split objects into young
and old based on whether
they survive a garbage
collection run.!
• concentrate on freeing up
memory on the young
generation.!

41. Why "Restricted"?!
• still using Mark and Sweep
to garbage collect young/
old generations!
• preserve compatibility with
C extensions!

43. Ojbect
Allocation
Tracing

44. require 'objspace'!
!
class Post!
def initialize(title)!
@title = title!
end!
!
def tags!
%w(ruby programming code).map do |tag|!
tag.upcase!
end!
end!
end!

45. Object Allocation Tracing!
ObjectSpace.trace_object_allocations_start!
a = Post.new("title")!
b = a.tags!
ObjectSpace.trace_object_allocations_stop!
!
!
ObjectSpace.allocation_sourcefile(b) # post.rb!
ObjectSpace.allocation_sourceline(b) #
ObjectSpace.allocation_class_path(b) # Array!
ObjectSpace.allocation_method_id(b) # map!

46. Ojbect
Allocation
Tracing
gives only raw data.!

47. gem install
allocation_stats!
https://github.com/srawlins/
allocation_stats!

48. require 'allocation_stats'!
!
class Post!
def initialize(title)!
@title = title!
end!
!
def tags!
%w(ruby programming code).map do |tag|!
tag.upcase!
end!
end!
end!
!
stats = AllocationStats.trace do!
post = Post.new("title")!
post.tags!
end!
!
puts stats.allocations(alias_paths: true).to_text!

49. Object Allocation Tracing!
sourcefile
---------post.rb
post.rb
post.rb
post.rb
post.rb
post.rb
post.rb
post.rb
post.rb
post.rb
sourceline
---------10
10
10
9
9
9
9
9
17
17
class_path
---------String
String
String
Array
Post
Post
Post
Post
Class
method_id
--------upcase
upcase
upcase
map
tags
tags
tags
tags
new
memsize
------0
0
0
0
0
0
0
0
0
0
class!
------!
String!
String!
String!
Array!
Array!
String!
String!
String!
Post!
String!

51. gem install
allocation_stats!
https://github.com/srawlins/
allocation_stats!

52. What's New?!
1.
!
2.
3.
4.
5.
6.
Rational Number & Complex
Number Literals !
def‘s return value!
Refinements!
Required Keyword Arguments!
Garbage Collector!
Object Allocation Tracing!

53. USE Ruby 2.1!

54. FOllow me on
twitter!
@bentanweihao!

55. Learn to build your own concurrent, distributed
web application – The fun & easy way!
http://www.exotpbook.com/!

56. Thanks! <3
@bentanweihao
benjamintanweihao.github.io!