Short presentation about Ruby 2.0 which I gave at a local Ruby meetup group.

1. RUBY 2.0
ugisozols.com

2. Refinments
module
StringPatch
refine
String
do
def
is_number?
!!match(/^d+$/)
end
end
end
"1".is_number?
#
=>
undefined
method
`is_number?'
...
using
StringPatch
"1".is_number?
#
=>
true
"a".is_number?
#
=>
false

3. Refinments
$
ruby
string_patch.rb
string_patch.rb:2:
warning:
Refinements
are
experimental,
and
the
behavior
may
change
in
future
versions
of
Ruby!

4. Module#prepend
module
A
def
foo;
puts
"A";
end
end
class
B
include
A
def
foo;
puts
"B";
end
end
klass
=
B.new
klass.foo
#
=>
"B"
B.ancestors
#
=>
[B,
A,
Object,
Kernel,
BasicObject]

5. Module#prepend
module
A
def
foo;
puts
"A";
end
end
class
B
prepend
A
#
<-­‐
prepend
instead
of
include
def
foo;
puts
"B";
end
end
klass
=
B.new
klass.foo
#
=>
"A"
B.ancestors
#
=>
[A,
B,
Object,
Kernel,
BasicObject]

6. Module#prepend
require
"active_support/core_ext/module/aliasing"
class
A
def
foo;
puts
"foo";
end
end
class
A
def
foo_with_bar
foo_without_bar
puts
"bar"
end
alias_method_chain
:foo,
:bar
end
A.new.foo
#
=>
"foo
bar"
A.ancestors
#
=>
[A,
Object,
Kernel,
BasicObject]

7. Module#prepend
class
A
def
foo;
puts
"foo";
end
end
module
Extension
def
foo
super
puts
"bar"
end
end
class
A
prepend
Extension
end
A.new.foo
#
=>
"foo
bar"
A.ancestors
#
=>
[Extension,
A,
Object,
Kernel,
BasicObject]

8. Keyword Arguments
def
link_to(name,
url_options
=
{},
html_options
=
{})
puts
"name
=
#{name.inspect}"
puts
"url_options
=
#{url_options.inspect}"
puts
"html_options
=
#{html_options.inspect}"
end
link_to("Ruby
1.9",
{},
{:class
=>
"styled-­‐link"})
#
name
=
"Ruby
1.9"
#
url_options
=
{}
#
html_options
=
{:class=>"styled-­‐link"}

9. Keyword Arguments
def
link_to(name,
url_options:
{},
html_options:
{})
puts
"name
=
#{name.inspect}"
puts
"url_options
=
#{url_options.inspect}"
puts
"html_options
=
#{html_options.inspect}"
end
link_to("Ruby
2.0",
:html_options
=>
{:class
=>
"styled-­‐link"})
#
name
=
"Ruby
2.0"
#
url_options
=
{}
#
html_options
=
{:class=>"styled-­‐link"}

10. Keyword Arguments
def
temperature(celsius,
fahrenheit:
to_fahrenheit(celsius))
puts
"#{celsius}°C"
puts
"#{fahrenheit}°F"
end
def
to_fahrenheit(celsius)
celsius
*
9
/
5
+
32
end
temperature(36)
#
36°C
#
96°F

11. Enumerable#lazy
words
=
File.open('/usr/share/dict/words')
.map(&:chomp)
.reject
{
|word|
word.length
<
4
}
.take(10)
words
#
=>
["aalii",
"Aani",
"aardvark",
...]
#
time
ruby
lazy.rb
~
0.22s

12. Enumerable#lazy
words
=
File.open('/usr/share/dict/words')
.lazy
#
<-­‐-­‐
added
lazy
here
.map(&:chomp)
.reject
{
|word|
word.length
<
4
}
.take(10)
words
#
=>
#<Enumerator::Lazy:
...]
words.to_a
#
=>
["aalii",
"Aani",
"aardvark",
...]
#
time
ruby
lazy.rb
~
0.06s

13. Enumerable#lazy
require
"fruity"
range
=
1..100
compare
do
without_lazy
{
range.
map
{
|el|
el
*
2
}
}
with_lazy
{
range.lazy.map
{
|el|
el
*
2
}.to_a
}
end
#
Running
each
test
256
times.
#
without_lazy
is
faster
than
with_lazy
by
4x
±
0.1

14. %i and %I symbol literals
%i(foo
bar
baz)
#
=>
[:foo,
:bar,
:baz]
%I(foo
b#{2+2}r
baz)
#
=>
[:foo,
:b4r,
:baz]

15. Default source encoding is
UTF-8
#
Ruby
1.9
#
encoding:
utf-­‐8
#
without
^
next
line
will
throw
"invalid
multibyte
char
(US-­‐
ASCII)"
name
=
"Uģis
Ozols"
#
Ruby
2.0
name
=
"Uģis
Ozols"

16. #to_h
Ruby
=
Struct.new(:version)
ruby
=
Ruby.new("2.0")
ruby.to_h
#
=>
{
:version
=>
"2.0"
}
def
config(options)
if
options.respond_to?(:to_h)
#
consume
hash
else
raise
TypeErorr,
"Can't
convert
#{options.inspect}
into
Hash"
end
end

17. #respond_to? returns
false for protected methods
class
A
protected
def
foo
"A"
end
end
klass
=
A.new
klass.respond_to?(:foo)
#=>
false
klass.respond_to?(:foo,
true)
#=>
true

18. #require optimizations
Rails
4.0.0.beta1
application
rails
g
scaffold
user
name
time
rake
test Ruby
1.9.3-­‐p392
~
12
seconds
time
rake
test Ruby
2.0.0-­‐p0
~
5
seconds

19. Thank you for listening!
ugisozols.com