Presented at the Ruby Drink-up of Sophia Antipolis on the 5th of February 2013 by Philippe Antras (@_philant_).

1. Ruby 2.0
bootstrap for discussion
Philippe Antras
@_philant_ Riviera.rb

2. The version number goes up to 2.0 but
the changes are rather small. Smaller
than the ones we made in 1.9.
Matz

3. refinements
experimental
localized monkey patching
refinements are file scope
only top-level "using" is available
no module scope refinement
no refinement inheritance

4. refinement example
module MyModule
refine String do
def price?
self.include? "$"
end
end
end
using MyModule
p "$13".price?

5. keyword arguments
(named parameters)
mandatory arguments
default values
parameter validation
list (with splat operator)
readability

6. def ruby_drinkup(topics, # mandatory
where: "the Green King",
date: "02/05/13",
time: "18:30",
announced: false,
booked: false)
...
end
ruby_drinkup(["rubinius", "ruby 2.0"])
ruby_drinkup(["???"], date: "03/05/13")
ruby_drinkup(["rubinius", "ruby 2.0"],
reserved: true,
announced: false)

7. lazy enumerators
build an internal block and iterates only once
enumerate infinite or very large datasets
iterate on a file without loading it all
map
flat_map
select
reject
grep
zip
take
take_while
drop
drop_while
cycle

8. next drinkup dates ?
def first_tuesday?(date)
date.tuesday? && date.day <= 7
end
drinkups =
Date.today..Float::INFINITY
.lazy
.select { |day| first_tuesday?(day) }
.take_while { |day| day.year == 2013 }
.force
puts drinkups

9. lines = File.foreach(BIG_FILE)
.lazy
.select { |line| line.match /ERR/ }
.take(10)
.to_a

10. rails

11. takeaway
2.0.0-rc2 delayed yesterday
refinements, safer, cleaner, but experimental
keyword arguments
lazy enumerators
compatible with Rails 3.2

12. so, what's new ?
module#prepend
declarations of the module overwrite those in the class
Array#bsearch { |x| block }
elements have to be ordered or nil is returned
Enumerator#size, Range#size
#to_h
convert Struct and OpenStruct to Hash
%i and %I
%i{one two three} => [:one, :two, :three]
Dtrace support

13. what changed ?
onigmo (new regex engine)
positive and negative lookbehind, named captures, backreferences improved
garbage collector
bitmap marking, smaller memory footprint
psych (use libyaml)
default encoding now is UTF-8
respond_to? returns false for protected methods
iconv has been removed
use String#encode instead

14. references
for more details:
https://bugs.ruby-lang.org/projects/ruby-trunk/roadmap#2.0.0
https://github.com/ruby/ruby/blob/v2_0_0_rc1/NEWS
https://bugs.ruby-lang.org/projects/ruby-trunk/wiki/RefinementsSpec
http://blog.headius.com/2012/11/refining-ruby.html
http://ruby-doc.org/core-2.0/Enumerator/Lazy.html
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/51301
http://patshaughnessy.net/2012/3/23/why-you-should-be-excited-about-
garbage-collection-in-ruby-2-0
http://www.ruby-forum.com/topic/4409612
http://www.ruby-forum.com/topic/4408480
http://globaldev.co.uk/2012/11/ruby-2-0-0-preview-features/
https://speakerdeck.com/a_matsuda/ruby-2-dot-0-on-rails

15. wanna give it a try ?
thank you