Peter Cooper
February 25, 2013
10k

# Ruby 2.0 Walkthrough: The Best Bits

A quick overview of a few of the best bits in Ruby 2.0.

## Peter Cooper

February 25, 2013

## Transcript

6. ### module FloatDivision refine Fixnum do def /(other); self.to_f / other;

end end end class MathFun using FloatDivision def self.ratio(a, b) a / b end end p MathFun.ratio(6, 8) THE OLD IDEA (no longer works)
7. ### module FloatDivision refine Fixnum do def /(other); self.to_f / other;

end end end class MathFun using FloatDivision def self.ratio(a, b) a / b end end p MathFun.ratio(6, 8)
8. ### module FloatDivision refine Fixnum do def /(other); self.to_f / other;

end end end using FloatDivision class MathFun def self.ratio(a, b) a / b end end p MathFun.ratio(6, 8) Main context is OK

10. ### def some_method(options = {}) defaults = { x: 10, y:

20, z: 30 } options = defaults.merge(options) p options end some_method x: 1, y: 2
11. ### def some_method(x: 10, y: 20, z: 30) p x, y,

z end some_method x: 1, y: 2, z: 3
12. ### def some_method(x: 10, **rest) p x, rest end some_method x:

1, y: 2, z: 3, c: “x”

0 }
15. ### infinite_range = (0..Float::INFINITY) e = infinite_range.lazy.select { |num| num %

74 == 0 } puts e.next puts e.next puts e.next

17. ### module Bar def my_method "inside the module" end end class

Foo include Bar def my_method "inside the class" super end end x = Foo.new p x.my_method 1 2
18. ### module Bar def my_method "inside the module" super end end

class Foo prepend Bar def my_method "inside the class" end end x = Foo.new p x.my_method 1 2
19. ### INCLUDE PREPEND Foo class Bar module x object NEITHER Foo

class x object Object class Object class Foo class Bar module x object Object class

24. ### RubyGems 2.0 Lots of refactoring, initial support for stdlib gemification,

gem search is now remote, arbitrary metadata support & more.

26. ### %i and %I To form arrays of symbols, like %w

does for words and arrays
27. ### %i{a b c} == [:a, :b, :c] %I{ #{(rand(26) +

65).chr} } == [:Y]
28. ### UTF-8 is default source encoding No more # encoding: utf-8

(if you don’t want)

30. ### CSV.load and CSV.dump gone Not considered such a good idea

in light of the early 2013 YAML vulnerabilities
31. ### String#chars, #lines, #codepoints, etc. Now return arrays rather than enumerators.

Use #each_char, #each_line, etc. instead if you need enumerators.

33. ### tracer = lambda do |event, file, line, id, binding, klass|

to_display = [event, File.basename(file), line, klass, id] puts "%10s in %s at line %-2d %s:%s" % to_display end set_trace_func tracer # .. normal code here ..
34. ### tracer = TracePoint.new do |tp| to_display = [tp.event, File.basename(tp.path), tp.lineno,

tp.defined_class, tp.method_id] puts "%10s in %s at line %-2d %s:%s" % to_display end tracer.enable # .. normal code here ..

p foo

39. ### [1, 4, 9, 13, 14, 22, 40].bsearch { |i| p

i; i >= 6 } # 13 # 4 # 9 # => 9 (1..1000).bsearch { |i| i > 372 }
40. ### __dir__ Like __FILE__ but for the current source file’s directory

Equivalent to File.dirname(File.realpath(__FILE__))
41. ### to_h and Hash() A new convention. The hash equivalent to

#to_a A key use is with Struct and OpenStruct
42. ### User = Struct.new(:name, :age, :status) me = User.new("Peter", 31, :admin)

me.to_h ENV.to_h Hash(nil) # => {} Hash([]) # => {}