Ruby 2.0

ALL THE THINGS

https://slid.es/sgerrand/ruby-2-0-all-the-things

Sasha Gerrand

@sgerrand

tl;dr

1.8.7 is officially EOL'd
2.0.0 is (noticeably) faster than 1.9.3
(GC, Float ops, Kernel#require, VM optimizations)
Drop-in replacement
100% compatible with 1.9.3
New language core features
(keyword args, Module#prepend, %i literal, __dir__, etc)
New built-in library features
(Enumerable#lazy, #to_h, etc)
Debug support
DTrace and TracePoint support

Embrace the awesome

NEW LANGUAGE CORE FEATURES

KEYWORD ARGUMENTS

Current idiom:

def my_method(argument1, argument2, opts = {})
  opts[:value] ||= 1
end

New style:

def my_method(argument1, argument2, value: 1, *a, **kw)
  # assign away
end

Array to argument list using splat (*) operator
Hash to keyword arguments using double splat (**)

Module#prepend

No need to use alias_method_chain or monkey patching

module A
  def self.prepended(mod)
    puts "#{self} prepended to #{mod}"
  end
end
module Enumerable
  prepend A
end
 # => prints "A prepended to Enumerable"

New array of symbols literals

%i (interpolation disabled)

%i[one one-hundred\ one]
#=> [:one, :"one-hundred one"]

%I (interpolation allowed)

%w[one one-hundred\ #{2 * 10}]
#=> ["one", "one-hundred 20"]

dir

New Kernel method, __dir__
Equivalent to File.dirname(File.realpath(__FILE__))

UTF-8 as default encoding

Finally the default file encoding

①, ②, ③ GO!

New Core Library Features

#to_h (finally)

Available in these classes:

Hash (surprise!)
NilClass
Struct

Customer = Struct.new(:name, :address, :zip)
sasha = Customer.new("Sasha Gerrand", "1 Kent St, Sydney NSW", 2000)
sasha.to_h[:address]   #=> "1 Kent St, Sydney NSW"

#LAZY evaluation

Current idiom:

module Enumerable
  def filter_map(&block)
    map(&block).compact
  end
end

New style:

class Enumerator::Lazy
  def filter_map
    Lazy.new(self) do |yielder, *values|
      result = yield *values
      yielder << result if result
    end
  end
end

(1..Float::INFINITY).lazy.filter_map{|i| i*i if i.even?}.first(5)
    # => [4, 16, 36, 64, 100]

#size of things

Enumerator#size

(1..100).to_a.permutation(4).size # => 94109400
loop.size # => Float::INFINITY
(1..100).drop_while.size # => nil

Range#size

(10..20).size    #=> 11

Onigmo

New regular expression engine*
Replaces Onigurama (standard in 1.9)
Supports new features from Perl 5.10+

* https://github.com/k-takata/Onigmo

AsyncHRONOUS exception handling

Finer control over Thread#raise and Thread#kill

Thread.handle_interrupt

th = Thread.new do
  Thread.handle_interrupt(RuntimeError => :never) {
    begin
      # You can write resource allocation code safely.
      Thread.handle_interrupt(RuntimeError => :immediate) {
        # ...
      }
    ensure
      # You can write resource deallocation code safely.
    end
  }
end
Thread.pass
# ...
th.raise "stop"

Enough rambling

Go forth: install or upgrade!

Default Ruby interpreter on OS X 'Mavericks'
Other options:

chruby
rbenv
RVM
RubyInstaller
compile from source

Questions?

Thanks

Happy 20th birthday, Ruby!