Ruby 1.9 changes, cherry picked-优快云博客

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Some of the most important improvements in ruby 1.9

Much better threading – performance and tools are superior to ruby 1.8. Read more about threads and fibers atPaul Barry’s blog.
Unicode support, finally. Also a brand new encoding engine has been added. There’s a very informative blog post about this onYehuda Katz’s blog.
The interpreter’s performance had been vastly improved. Check out the (v1.9.0)benchmark.
Rubygems is now integrated into ‘ruby’ itself.

Let’s look at the main incompatibilites that can break your code

The shiny new String class.
Literal Hash constructor has changed.
- {“a”, “b”} no longer makes a Hash but a nice syntax error. You have to use {“a” => “b”} or {:a => “b”} or {a: “b”}

Now for the other important changes and upgrades

Changes in the Hash class

Hash finally preserves insertion order

Ruby 1.8

^? View Code RUBY

hash = {:a=> 'A', :b=>'B', :c=>'C', :d=>'D'}
hash.keys ====>  [:b, :c, :d, :a]
hash.values ====> ["B", "C", "D", "A"]

Ruby 1.9

^? View Code RUBY

hash = {:a=> 'A', :b=>'B', :c=>'C', :d=>'D'}
hash.keys ====>  [:a, :b, :c, :d]
hash.values ====> ["A", "B", "C", "D"]

Hash#to_s behaves much nicer

Ruby 1.8

^? View Code RUBY

hash = {:a=> 1, :b=>2, :c=>3, :d=>4}
hash.to_s ====> "b2c3d4a1"

Ruby 1.9

^? View Code RUBY

hash = {:a=> 1, :b=>2, :c=>3, :d=>4}
hash.to_s ====> "{:a=>1, :b=>2, :c=>3, :d=>4}"

Hash#select now returns a hash, not an array

Ruby 1.8

^? View Code RUBY

hash = {:a=> 1, :b=>2, :c=>3, :d=>4}
hash.select{|k,v| k == :c }  ====> [[:c, 3]]

Ruby 1.9

^? View Code RUBY

hash = {:a=> 1, :b=>2, :c=>3, :d=>4}
hash.select{|k,v| k == :c } ====> {:c=>3}

String changes

Single character strings

Ruby 1.8

^? View Code RUBY

irb(main):001:0> ?c
=> 99	    
irb(main):001:0> "cat"[1]
=> 97

Ruby 1.9

^? View Code RUBY

irb(main):001:0> ?c
=> "c"
irb(main):001:0> "cat"[1]
=> "a"

Encoding, encoding, encoding

All strings have an additional chunk of info attached: Encoding

^? View Code RUBY

ruby-1.9.2-p136 :003 > "whatever".encoding
 => #<Encoding:UTF-8> 
ruby-1.9.2-p136 :004 > "whatever".encoding.name
 => "UTF-8"

String#size takes encoding into account – returns the encoded character count

^? View Code RUBY
puts utf8_string.size # >> 6 puts latin1_string.size # >> 6

You can get the raw datasize

^? View Code RUBY

puts utf8_string.bytesize    # >> 8
puts latin1_string.bytesize  # >> 6

Indexed access is by encoded data – characters, not bytes

^? View Code RUBY

puts utf8_string[2..4]    # >> sum
puts latin1_string[2..4]  # >> sum

You can change encoding by force but it doesn’t convert the data

^? View Code RUBY

my_string = "Whatever"
puts my_string.encoding.name  # >> US-ASCII
my_string.force_encoding("UTF-8")
puts my_string.encoding.name  # >> UTF-8

# changing the encoding doesn't convert the data though!
latin1_string.force_encoding("UTF-8")
puts latin1_string.encoding.name    # >> UTF-8
puts latin1_string.bytesize         # >> 6
puts latin1_string.valid_encoding?  # >> false
latin1_string =~ /AR/  # !> ArgumentError: invalid byte sequence in UTF-8

You can re-encode a string to ‘fix’ the above ‘error’

^? View Code RUBY

transcoded_utf8_string= latin1_string.encode("UTF-8")
puts transcoded_utf8_string.valid_encoding?  # >> true

Iterators have changed as String is not Enumerable anymore

^? View Code RUBY

#Use each_byte, each_char or each_codepoint

utf8_resume.each_byte do |byte|
  puts byte
end
# >> 82
# >> 195
# >> 169
# >> 115
# >> 117
# >> 109
# >> 195
# >> 169

utf8_resume.each_char do |char|
  puts char
end
# >> R
# >> é
# >> s
# >> u
# >> m
# >> é

utf8_resume.each_codepoint do |codepoint|
  puts codepoint
end
# >> 82
# >> 233
# >> 115
# >> 117
# >> 109
# >> 233

# if you need custom processing, you can get the enumerators with bytes, chars, lines and codepoints

p utf8_resume.bytes.first(3)
# >> [82, 195, 169]
p utf8_resume.chars.find { |char| char.bytesize > 1 }
# >> "é"
p utf8_resume.codepoints.to_a
# >> [82, 233, 115, 117, 109, 233]
p utf8_resume.lines.map { |line| line.reverse }
# >> ["émuséR"]

Block variables now shadow local variables

^? View Code RUBY

#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

tr and Regexp are Unicode-compatible

You can now specify source file encoding

Basic

# coding: utf-8
Emacs

# -*- encoding: utf-8 -*-
Shebang

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

Inject methods

^? View Code RUBY

#Ruby 1.9

[1,2].inject(:+)

#Ruby 1.8.6

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

Lambda shorthand syntax

^? View Code RUBY

#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)

Complex numbers

^? View Code RUBY

#Ruby 1.9

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

Multi-splat

^? View Code RUBY

# This will work on both Ruby 1.8 and 1.9
a, b, c = *[1, 2], 3

# This will fail on 1.8, but work on 1.9
a, b, c = 1, *[2, 3]

# Even this will work on 1.9, but not 1.8
a, b, c, d, e, f = *[1, 2], 3, *[4, 5]

Blocks now can accept block arguments

^? View Code RUBY

define_method(:answer) { |&b| b.call(42) }