Collection of ruby (and ruby related) tricks

1. ruby
off the beaten path
github.com/julio

2. ruby things

3. 01
string concatenation

4. 1.8.7-p358 :001 > s = “this” “is” “a” “thing”

5. 1.8.7-p358 :001 > s = “this” “is” “a” “thing”
=> “thisisathing”
1.8.7-p358 :002 >

6. 02
print json

7. 1.8.7-p358 :001 > require “rubygems”
=> true
1.8.7-p358 :002 > require “json”
=> true
1.8.7-p358 :003 > h = {:one => 1, :two => 2}
=> {:one=>1, :two=>2}
1.8.7-p358 :004 > j h

8. 1.8.7-p358 :001 > require “rubygems”
=> true
1.8.7-p358 :002 > require “json”
=> true
1.8.7-p358 :003 > h = {:one => 1, :two => 2}
=> {:one=>1, :two=>2}
1.8.7-p358 :004 > j h
{"one":1,"two":2}

9. 1.8.7-p358 :001 > require “rubygems”
=> true
1.8.7-p358 :002 > require “json”
=> true
1.8.7-p358 :003 > h = {:one => 1, :two => 2}
=> {:one=>1, :two=>2}
1.8.7-p358 :004 > j h
{"one":1,"two":2}
1.8.7-p358 :005 > jj h

10. 1.8.7-p358 :001 > require “rubygems”
=> true
1.8.7-p358 :002 > require “json”
=> true
1.8.7-p358 :003 > h = {:one => 1, :two => 2}
=> {:one=>1, :two=>2}
1.8.7-p358 :004 > j h
{"one":1,"two":2}
1.8.7-p358 :005 > jj h
{
"one": 1,
"two": 2
}
1.8.7-p358 :006 >

11. 03
interpolation

12. 1.8.7-p358 :001 > @name = "bob"
=> “bob”
1.8.7-p358 :002 > puts "hello #@name"

13. 1.8.7-p358 :001 > @name = "bob"
=> “bob”
1.8.7-p358 :002 > puts "hello #@name"
“hello bob”
=> nil

14. 04
.. and ...

15. 1.8.7-p358 :001 > a = (1..2)
=> 1..2

16. 1.8.7-p358 :001 > a = (1..2)
=> 1..2
1.8.7-p358 :002 > a.to_a

17. 1.8.7-p358 :001 > a = (1..2)
=> 1..2
1.8.7-p358 :002 > a.to_a
=> [1, 2]

18. 1.8.7-p358 :001 > a = (1..2)
=> 1..2
1.8.7-p358 :002 > a.to_a
=> [1, 2]
1.8.7-p358 :003 > b = (1...2)

19. 1.8.7-p358 :001 > a = (1..2)
=> 1..2
1.8.7-p358 :002 > a.to_a
=> [1, 2]
1.8.7-p358 :003 > b = (1...2)
=> 1...2

20. 1.8.7-p358 :001 > a = (1..2)
=> 1..2
1.8.7-p358 :002 > a.to_a
=> [1, 2]
1.8.7-p358 :003 > b = (1...2)
=> 1...2
1.8.7-p358 :004 > b.to_a

21. 1.8.7-p358 :001 > a = (1..2)
=> 1..2
1.8.7-p358 :002 > a.to_a
=> [1, 2]
1.8.7-p358 :003 > b = (1...2)
=> 1...2
1.8.7-p358 :004 > b.to_a
=> [1]

22. 05
string contains?

23. 1.8.7-p358 :001 > s = "this is a string"
=> “this is a string”
1.8.7-p358 :002 > s[“is a”]

24. 1.8.7-p358 :001 > s = "this is a string"
=> “this is a string”
1.8.7-p358 :002 > s[“is a”]
=> “is a”

25. 1.8.7-p358 :001 > s = "this is a string"
=> “this is a string”
1.8.7-p358 :002 > s[“is a”]
=> “is a”
1.8.7-p358 :003 > s["is not a"]

26. 1.8.7-p358 :001 > s = "this is a string"
=> “this is a string”
1.8.7-p358 :002 > s[“is a”]
=> “is a”
1.8.7-p358 :003 > s["is not a"]
=> nil

27. 06
expand array

28. 1.8.7-p358 :001 > [*10..20]

29. 1.8.7-p358 :001 > [*10..20]
=> [10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]

30. 07
hash from array

31. 1.8.7-p358 :001 > Hash[1,2,3,4]

32. 1.8.7-p358 :001 > Hash[1,2,3,4]
=> {1=>2, 3=>4}

33. 1.8.7-p358 :001 > Hash[1,2,3,4]
=> {1=>2, 3=>4}
1.8.7-p358 :002 > Hash[["one", 1], ["two", 2]]

34. 1.8.7-p358 :001 > Hash[1,2,3,4]
=> {1=>2, 3=>4}
1.8.7-p358 :002 > Hash[["one", 1], ["two", 2]]
=> {["one", 1]=>["two", 2]}

35. 1.8.7-p358 :001 > Hash[1,2,3,4]
=> {1=>2, 3=>4}
1.8.7-p358 :002 > Hash[["one", 1], ["two", 2]]
=> {["one", 1]=>["two", 2]}
1.8.7-p358 :003 > a=["one", 1], ["two", 2]

36. 1.8.7-p358 :001 > Hash[1,2,3,4]
=> {1=>2, 3=>4}
1.8.7-p358 :002 > Hash[["one", 1], ["two", 2]]
=> {["one", 1]=>["two", 2]}
1.8.7-p358 :003 > a=["one", 1], ["two", 2]
=> [["one", 1], ["two", 2]]

37. 1.8.7-p358 :001 > Hash[1,2,3,4]
=> {1=>2, 3=>4}
1.8.7-p358 :002 > Hash[["one", 1], ["two", 2]]
=> {["one", 1]=>["two", 2]}
1.8.7-p358 :003 > a=["one", 1], ["two", 2]
=> [["one", 1], ["two", 2]]
1.8.7-p358 :004 > Hash[a]

38. 1.8.7-p358 :001 > Hash[1,2,3,4]
=> {1=>2, 3=>4}
1.8.7-p358 :002 > Hash[["one", 1], ["two", 2]]
=> {["one", 1]=>["two", 2]}
1.8.7-p358 :003 > a=["one", 1], ["two", 2]
=> [["one", 1], ["two", 2]]
1.8.7-p358 :004 > Hash[a]
=> {"two"=>2, "one"=>1}
1.8.7-p358 :005 > b = [1,2,3,4]

39. 1.8.7-p358 :001 > Hash[1,2,3,4]
=> {1=>2, 3=>4}
1.8.7-p358 :002 > Hash[["one", 1], ["two", 2]]
=> {["one", 1]=>["two", 2]}
1.8.7-p358 :003 > a=["one", 1], ["two", 2]
=> [["one", 1], ["two", 2]]
1.8.7-p358 :004 > Hash[a]
=> {"two"=>2, "one"=>1}
1.8.7-p358 :005 > b = [1,2,3,4]
=> [1,2,3,4]

40. 1.8.7-p358 :001 > Hash[1,2,3,4]
=> {1=>2, 3=>4}
1.8.7-p358 :002 > Hash[["one", 1], ["two", 2]]
=> {["one", 1]=>["two", 2]}
1.8.7-p358 :003 > a=["one", 1], ["two", 2]
=> [["one", 1], ["two", 2]]
1.8.7-p358 :004 > Hash[a]
=> {"two"=>2, "one"=>1}
1.8.7-p358 :005 > b = [1,2,3,4]
=> [1,2,3,4]
1.8.7-p358 :006 > Hash[*b]

41. 1.8.7-p358 :001 > Hash[1,2,3,4]
=> {1=>2, 3=>4}
1.8.7-p358 :002 > Hash[["one", 1], ["two", 2]]
=> {["one", 1]=>["two", 2]}
1.8.7-p358 :003 > a=["one", 1], ["two", 2]
=> [["one", 1], ["two", 2]]
1.8.7-p358 :004 > Hash[a]
=> {"two"=>2, "one"=>1}
1.8.7-p358 :005 > b = [1,2,3,4]
=> [1,2,3,4]
1.8.7-p358 :006 > Hash[*b]
=> {1=>2, 3=>4}

42. 08
zip

43. 1.8.7-p358 :001 > keys = [:one, :two, :three]
=> [:one, :two, :three]
1.8.7-p358 :002 > values = [1,2,3]
=> [1, 2, 3]
1.8.7-p358 :003 > zip = keys.zip(values)

44. 1.8.7-p358 :001 > keys = [:one, :two, :three]
=> [:one, :two, :three]
1.8.7-p358 :002 > values = [1,2,3]
=> [1, 2, 3]
1.8.7-p358 :003 > zip = keys.zip(values)
=> [[:one, 1], [:two, 2], [:three, 3]]

45. 1.8.7-p358 :001 > keys = [:one, :two, :three]
=> [:one, :two, :three]
1.8.7-p358 :002 > values = [1,2,3]
=> [1, 2, 3]
1.8.7-p358 :003 > zip = keys.zip(values)
=> [[:one, 1], [:two, 2], [:three, 3]]
1.8.7-p358 :004 > Hash[zip]

46. 1.8.7-p358 :001 > keys = [:one, :two, :three]
=> [:one, :two, :three]
1.8.7-p358 :002 > values = [1,2,3]
=> [1, 2, 3]
1.8.7-p358 :003 > zip = keys.zip(values)
=> [[:one, 1], [:two, 2], [:three, 3]]
1.8.7-p358 :004 > Hash[zip]
=> {:two=>2, :three=>3, :one=>1}

47. 09
shuffle

48. 1.8.7-p358 :001 > a = [1,2,3]
=> [1, 2, 3]
1.8.7-p358 :002 > a.shuffle

49. 1.8.7-p358 :001 > a = [1,2,3]
=> [1, 2, 3]
1.8.7-p358 :002 > a.shuffle
=> [1, 3, 2]

50. 1.8.7-p358 :001 > a = [1,2,3]
=> [1, 2, 3]
1.8.7-p358 :002 > a.shuffle
=> [1, 3, 2]
1.8.7-p358 :003 > a.shuffle

51. 1.8.7-p358 :001 > a = [1,2,3]
=> [1, 2, 3]
1.8.7-p358 :002 > a.shuffle
=> [1, 3, 2]
1.8.7-p358 :003 > a.shuffle
=> [3, 2, 1]

52. 10
cons

53. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > a.each_cons(2) {|pair| p pair}

54. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > a.each_cons(2) {|pair| p pair}
[1, 2]
[2, 3]
[3, 4]
[4, 5]
=> nil

55. 11
set

56. 1.8.7-p358 :001 > require 'set'
=> true
1.8.7-p358 :002 > s = Set.new
=> #<Set: {}>
1.8.7-p358 :003 > s << 1

57. 1.8.7-p358 :001 > require 'set'
=> true
1.8.7-p358 :002 > s = Set.new
=> #<Set: {}>
1.8.7-p358 :003 > s << 1
=> #<Set: {1}>

58. 1.8.7-p358 :001 > require 'set'
=> true
1.8.7-p358 :002 > s = Set.new
=> #<Set: {}>
1.8.7-p358 :003 > s << 1
=> #<Set: {1}>
1.8.7-p358 :004 > s << 1

59. 1.8.7-p358 :001 > require 'set'
=> true
1.8.7-p358 :002 > s = Set.new
=> #<Set: {}>
1.8.7-p358 :003 > s << 1
=> #<Set: {1}>
1.8.7-p358 :004 > s << 1
=> #<Set: {1}>

60. 1.8.7-p358 :001 > require 'set'
=> true
1.8.7-p358 :002 > s = Set.new
=> #<Set: {}>
1.8.7-p358 :003 > s << 1
=> #<Set: {1}>
1.8.7-p358 :004 > s << 1
=> #<Set: {1}>
1.8.7-p358 :005 > s << 2

61. 1.8.7-p358 :001 > require 'set'
=> true
1.8.7-p358 :002 > s = Set.new
=> #<Set: {}>
1.8.7-p358 :003 > s << 1
=> #<Set: {1}>
1.8.7-p358 :004 > s << 1
=> #<Set: {1}>
1.8.7-p358 :005 > s << 2
=> #<Set: {1, 2}>

62. 12
include A, B, C

63. 1.8.7-p358 :001 > module A; def foo; "A"; end; end
=> nil

64. 1.8.7-p358 :001 > module A; def foo; "A"; end; end
=> nil
1.8.7-p358 :002 > module B; def foo; "B"; end; end
=> nil

65. 1.8.7-p358 :001 > module A; def foo; "A"; end; end
=> nil
1.8.7-p358 :002 > module B; def foo; "B"; end; end
=> nil
1.8.7-p358 :003 > class C; include A; include B; end
=> C

66. 1.8.7-p358 :001 > module A; def foo; "A"; end; end
=> nil
1.8.7-p358 :002 > module B; def foo; "B"; end; end
=> nil
1.8.7-p358 :003 > class C; include A; include B; end
=> C
1.8.7-p358 :004 > C.new.foo

67. 1.8.7-p358 :001 > module A; def foo; "A"; end; end
=> nil
1.8.7-p358 :002 > module B; def foo; "B"; end; end
=> nil
1.8.7-p358 :003 > class C; include A; include B; end
=> C
1.8.7-p358 :004 > C.new.foo
=> “B”

68. 1.8.7-p358 :001 > module A; def foo; "A"; end; end
=> nil
1.8.7-p358 :002 > module B; def foo; "B"; end; end
=> nil
1.8.7-p358 :003 > class C; include A; include B; end
=> C
1.8.7-p358 :004 > C.new.foo
=> “B”
1.8.7-p358 :005 > class D; include A, B; end

69. 1.8.7-p358 :001 > module A; def foo; "A"; end; end
=> nil
1.8.7-p358 :002 > module B; def foo; "B"; end; end
=> nil
1.8.7-p358 :003 > class C; include A; include B; end
=> C
1.8.7-p358 :004 > C.new.foo
=> “B”
1.8.7-p358 :005 > class D; include A, B; end
=> D

70. 1.8.7-p358 :001 > module A; def foo; "A"; end; end
=> nil
1.8.7-p358 :002 > module B; def foo; "B"; end; end
=> nil
1.8.7-p358 :003 > class C; include A; include B; end
=> C
1.8.7-p358 :004 > C.new.foo
=> “B”
1.8.7-p358 :005 > class D; include A, B; end
=> D
1.8.7-p358 :006 > D.new.foo

71. 1.8.7-p358 :001 > module A; def foo; "A"; end; end
=> nil
1.8.7-p358 :002 > module B; def foo; "B"; end; end
=> nil
1.8.7-p358 :003 > class C; include A; include B; end
=> C
1.8.7-p358 :004 > C.new.foo
=> “B”
1.8.7-p358 :005 > class D; include A, B; end
=> D
1.8.7-p358 :006 > D.new.foo
=> “A”

72. 13
default args

73. 1.8.7-p358 :001 > def foo(x, y=2); print x; print y; end
=> nil
1.8.7-p358 :002 > foo 1

74. 1.8.7-p358 :001 > def foo(x, y=2); print x; print y; end
=> nil
1.8.7-p358 :002 > foo 1
12 => nil

75. 1.8.7-p358 :001 > def foo(x, y=2); print x; print y; end
=> nil
1.8.7-p358 :002 > foo 1
12 => nil
1.8.7-p358 :003 > def bar(x, y=x); print x; print y; end
=> nil

76. 1.8.7-p358 :001 > def foo(x, y=2); print x; print y; end
=> nil
1.8.7-p358 :002 > foo 1
12 => nil
1.8.7-p358 :003 > def bar(x, y=x); print x; print y; end
=> nil
1.8.7-p358 :004 > bar 1

77. 1.8.7-p358 :001 > def foo(x, y=2); print x; print y; end
=> nil
1.8.7-p358 :002 > foo 1
12 => nil
1.8.7-p358 :003 > def bar(x, y=x); print x; print y; end
=> nil
1.8.7-p358 :004 > bar 1
11 => nil

78. 1.8.7-p358 :001 > def foo(x, y=2); print x; print y; end
=> nil
1.8.7-p358 :002 > foo 1
12 => nil
1.8.7-p358 :003 > def bar(x, y=x); print x; print y; end
=> nil
1.8.7-p358 :004 > bar 1
11 => nil
1.8.7-p358 :005 > bar 1,2

79. 1.8.7-p358 :001 > def foo(x, y=2); print x; print y; end
=> nil
1.8.7-p358 :002 > foo 1
12 => nil
1.8.7-p358 :003 > def bar(x, y=x); print x; print y; end
=> nil
1.8.7-p358 :004 > bar 1
11 => nil
1.8.7-p358 :005 > bar 1,2
12 => nil

80. 14
caller

81. 1.8.7-p358 :001 > def foo; puts caller; "foo"; end
=> nil

82. 1.8.7-p358 :001 > def foo; puts caller; "foo"; end
=> nil
1.8.7-p358 :002 > def bar; foo; end
=> nil

83. 1.8.7-p358 :001 > def foo; puts caller; "foo"; end
=> nil
1.8.7-p358 :002 > def bar; foo; end
=> nil
1.8.7-p358 :003 > bar

84. 1.8.7-p358 :001 > def foo; puts caller; "foo"; end
=> nil
1.8.7-p358 :002 > def bar; foo; end
=> nil
1.8.7-p358 :003 > bar
(irb):5:in `bar'
(irb):6:in `irb_binding'
/Users/julio/.rvm/rubies/ruby-1.8.7-p358/lib/ruby/1.8/irb/
workspace.rb:52:in `irb_binding'
/Users/julio/.rvm/rubies/ruby-1.8.7-p358/lib/ruby/1.8/irb/
workspace.rb:52
=> "foo"

85. 15
car and cdr

86. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]

87. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > car, *cdr = a

88. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > car, *cdr = a
=> [1, 2, 3, 4, 5]

89. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > car, *cdr = a
=> [1, 2, 3, 4, 5]
1.8.7-p358 :003 > car

90. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > car, *cdr = a
=> [1, 2, 3, 4, 5]
1.8.7-p358 :003 > car
=> 1

91. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > car, *cdr = a
=> [1, 2, 3, 4, 5]
1.8.7-p358 :003 > car
=> 1
1.8.7-p358 :004 > cdr

92. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > car, *cdr = a
=> [1, 2, 3, 4, 5]
1.8.7-p358 :003 > car
=> 1
1.8.7-p358 :004 > cdr
=> [2, 3, 4, 5]

93. 16
group_by

94. 1.8.7-p358 :001 > words = %w{ foo bar yo stuff }
=> ["foo", "bar", "yo", "stuff"]

95. 1.8.7-p358 :001 > words = %w{ foo bar yo stuff }
=> ["foo", "bar", "yo", "stuff"]
1.8.7-p358 :002 > words.group_by {|x| x.size}

96. 1.8.7-p358 :001 > words = %w{ foo bar yo stuff }
=> ["foo", "bar", "yo", "stuff"]
1.8.7-p358 :002 > words.group_by {|x| x.size}
=> {5=>["stuff"], 2=>["yo"], 3=>["foo", "bar"]}

97. 17
inject and reduce

98. 1.8.7-p358 :001 > a = [*1..100] # or (1..100).to_a
=> [1, 2, 3, 4, ..., 99, 100]

99. 1.8.7-p358 :001 > a = [*1..100] # or (1..100).to_a
=> [1, 2, 3, 4, ..., 99, 100]
1.8.7-p358 :002 > t = [*1..100].inject(0) {|a,e| a += e}

100. 1.8.7-p358 :001 > a = [*1..100] # or (1..100).to_a
=> [1, 2, 3, 4, ..., 99, 100]
1.8.7-p358 :002 > t = [*1..100].inject(0) {|a,e| a += e}
=> 5050

101. 1.8.7-p358 :001 > a = [*1..100] # or (1..100).to_a
=> [1, 2, 3, 4, ..., 99, 100]
1.8.7-p358 :002 > t = [*1..100].inject(0) {|a,e| a += e}
=> 5050
1.8.7-p358 :003 > t = [*1..100].inject {|a,e| a += e}
=> 5050

102. 1.8.7-p358 :001 > a = [*1..100] # or (1..100).to_a
=> [1, 2, 3, 4, ..., 99, 100]
1.8.7-p358 :002 > t = [*1..100].inject(0) {|a,e| a += e}
=> 5050
1.8.7-p358 :003 > t = [*1..100].inject {|a,e| a += e}
=> 5050
1.8.7-p358 :004 > t = [*1..100].inject(&:+)
=> 5050

103. 1.8.7-p358 :001 > a = [*1..100] # or (1..100).to_a
=> [1, 2, 3, 4, ..., 99, 100]
1.8.7-p358 :002 > t = [*1..100].inject(0) {|a,e| a += e}
=> 5050
1.8.7-p358 :003 > t = [*1..100].inject {|a,e| a += e}
=> 5050
1.8.7-p358 :004 > t = [*1..100].inject(&:+)
=> 5050
1.8.7-p358 :005 > t = [*1..100].inject(:+)
=> 5050

104. 1.8.7-p358 :001 > a = [*1..100] # or (1..100).to_a
=> [1, 2, 3, 4, ..., 99, 100]
1.8.7-p358 :002 > t = [*1..100].inject(0) {|a,e| a += e}
=> 5050
1.8.7-p358 :003 > t = [*1..100].inject {|a,e| a += e}
=> 5050
1.8.7-p358 :004 > t = [*1..100].inject(&:+)
=> 5050
1.8.7-p358 :005 > t = [*1..100].inject(:+)
=> 5050
1.8.7-p358 :006 > t = [*1..100].reduce(:+)
=> 5050

105. 18
the other join

106. 1.8.7-p358 :001 > a = [1,2,3,4]
=> [1, 2, 3, 4]

107. 1.8.7-p358 :001 > a = [1,2,3,4]
=> [1, 2, 3, 4]
1.8.7-p358 :002 > a *= ","

108. 1.8.7-p358 :001 > a = [1,2,3,4]
=> [1, 2, 3, 4]
1.8.7-p358 :002 > a *= ","
=> "1,2,3,4"

109. 19
add method to instance

110. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]

111. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > module Summable; def mul; self.reduce(:*); end;end
=> nil

112. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > module Summable; def mul; self.reduce(:*); end;end
=> nil
1.8.7-p358 :003 > a.extend Summable
=> [1, 2, 3, 4, 5]

113. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > module Summable; def mul; self.reduce(:*); end;end
=> nil
1.8.7-p358 :003 > a.extend Summable
=> [1, 2, 3, 4, 5]
1.8.7-p358 :004 > a.mul

114. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > module Summable; def mul; self.reduce(:*); end;end
=> nil
1.8.7-p358 :003 > a.extend Summable
=> [1, 2, 3, 4, 5]
1.8.7-p358 :004 > a.mul
=> 120

115. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > module Summable; def mul; self.reduce(:*); end;end
=> nil
1.8.7-p358 :003 > a.extend Summable
=> [1, 2, 3, 4, 5]
1.8.7-p358 :004 > a.mul
=> 120
1.8.7-p358 :005 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]

116. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > module Summable; def mul; self.reduce(:*); end;end
=> nil
1.8.7-p358 :003 > a.extend Summable
=> [1, 2, 3, 4, 5]
1.8.7-p358 :004 > a.mul
=> 120
1.8.7-p358 :005 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :006 > a.mul

117. 1.8.7-p358 :001 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :002 > module Summable; def mul; self.reduce(:*); end;end
=> nil
1.8.7-p358 :003 > a.extend Summable
=> [1, 2, 3, 4, 5]
1.8.7-p358 :004 > a.mul
=> 120
1.8.7-p358 :005 > a = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]
1.8.7-p358 :006 > a.mul
=> NoMethodError: undefined method `mul' for [1, 2, 3, 4, 5]:Array

118. 20
methods.grep

119. 1.8.7-p358 :001 > class C; def foo; "foo"; end; end
=> nil
1.8.7-p358 :002 > c = C.new
=> #<C:0x10b3e0b28>

120. 1.8.7-p358 :001 > class C; def foo; "foo"; end; end
=> nil
1.8.7-p358 :002 > c = C.new
=> #<C:0x10b3e0b28>
1.8.7-p358 :003 > c.methods.grep /foo/

121. 1.8.7-p358 :001 > class C; def foo; "foo"; end; end
=> nil
1.8.7-p358 :002 > c = C.new
=> #<C:0x10b3e0b28>
1.8.7-p358 :003 > c.methods.grep /foo/
=> ["foo"]

122. 21
class variables

123. 1.8.7-p358 :001 > class A; @@foo="A"; def self.foo; @@foo; end; end
=> nil

124. 1.8.7-p358 :001 > class A; @@foo="A"; def self.foo; @@foo; end; end
=> nil
1.8.7-p358 :002 > class C < A; nil; end
=> nil

125. 1.8.7-p358 :001 > class A; @@foo="A"; def self.foo; @@foo; end; end
=> nil
1.8.7-p358 :002 > class C < A; nil; end
=> nil
1.8.7-p358 :003 > A.foo

126. 1.8.7-p358 :001 > class A; @@foo="A"; def self.foo; @@foo; end; end
=> nil
1.8.7-p358 :002 > class C < A; nil; end
=> nil
1.8.7-p358 :003 > A.foo
=> “A”

127. 1.8.7-p358 :001 > class A; @@foo="A"; def self.foo; @@foo; end; end
=> nil
1.8.7-p358 :002 > class C < A; nil; end
=> nil
1.8.7-p358 :003 > A.foo
=> “A”
1.8.7-p358 :003 > C.foo

128. 1.8.7-p358 :001 > class A; @@foo="A"; def self.foo; @@foo; end; end
=> nil
1.8.7-p358 :002 > class C < A; nil; end
=> nil
1.8.7-p358 :003 > A.foo
=> “A”
1.8.7-p358 :003 > C.foo
=> “A”

129. 1.8.7-p358 :001 > class A; @@foo="A"; def self.foo; @@foo; end; end
=> nil
1.8.7-p358 :002 > class C < A; nil; end
=> nil
1.8.7-p358 :003 > A.foo
=> “A”
1.8.7-p358 :003 > C.foo
=> “A”
1.8.7-p358 :003 > class B < A; @@foo="B"; nil; end

130. 1.8.7-p358 :001 > class A; @@foo="A"; def self.foo; @@foo; end; end
=> nil
1.8.7-p358 :002 > class C < A; nil; end
=> nil
1.8.7-p358 :003 > A.foo
=> “A”
1.8.7-p358 :003 > C.foo
=> “A”
1.8.7-p358 :003 > class B < A; @@foo="B"; nil; end
=> nil

131. 1.8.7-p358 :001 > class A; @@foo="A"; def self.foo; @@foo; end; end
=> nil
1.8.7-p358 :002 > class C < A; nil; end
=> nil
1.8.7-p358 :003 > A.foo
=> “A”
1.8.7-p358 :003 > C.foo
=> “A”
1.8.7-p358 :003 > class B < A; @@foo="B"; nil; end
=> nil
1.8.7-p358 :003 > B.foo

132. 1.8.7-p358 :001 > class A; @@foo="A"; def self.foo; @@foo; end; end
=> nil
1.8.7-p358 :002 > class C < A; nil; end
=> nil
1.8.7-p358 :003 > A.foo
=> “A”
1.8.7-p358 :003 > C.foo
=> “A”
1.8.7-p358 :003 > class B < A; @@foo="B"; nil; end
=> nil
1.8.7-p358 :003 > B.foo
=> “B”

133. 1.8.7-p358 :001 > class A; @@foo="A"; def self.foo; @@foo; end; end
=> nil
1.8.7-p358 :002 > class C < A; nil; end
=> nil
1.8.7-p358 :003 > A.foo
=> “A”
1.8.7-p358 :003 > C.foo
=> “A”
1.8.7-p358 :003 > class B < A; @@foo="B"; nil; end
=> nil
1.8.7-p358 :003 > B.foo
=> “B”
1.8.7-p358 :003 > A.foo

134. 1.8.7-p358 :001 > class A; @@foo="A"; def self.foo; @@foo; end; end
=> nil
1.8.7-p358 :002 > class C < A; nil; end
=> nil
1.8.7-p358 :003 > A.foo
=> “A”
1.8.7-p358 :003 > C.foo
=> “A”
1.8.7-p358 :003 > class B < A; @@foo="B"; nil; end
=> nil
1.8.7-p358 :003 > B.foo
=> “B”
1.8.7-p358 :003 > A.foo
=> “B”

135. 1.8.7-p358 :001 > class A; @@foo="A"; def self.foo; @@foo; end; end
=> nil
1.8.7-p358 :002 > class C < A; nil; end
=> nil
1.8.7-p358 :003 > A.foo
=> “A”
1.8.7-p358 :003 > C.foo
=> “A”
1.8.7-p358 :003 > class B < A; @@foo="B"; nil; end
=> nil
1.8.7-p358 :003 > B.foo
=> “B”
1.8.7-p358 :003 > A.foo
=> “B”
1.8.7-p358 :003 > C.foo

136. 1.8.7-p358 :001 > class A; @@foo="A"; def self.foo; @@foo; end; end
=> nil
1.8.7-p358 :002 > class C < A; nil; end
=> nil
1.8.7-p358 :003 > A.foo
=> “A”
1.8.7-p358 :003 > C.foo
=> “A”
1.8.7-p358 :003 > class B < A; @@foo="B"; nil; end
=> nil
1.8.7-p358 :003 > B.foo
=> “B”
1.8.7-p358 :003 > A.foo
=> “B”
1.8.7-p358 :003 > C.foo
=> “B”

137. 22
int to hex to int

138. 1.8.7-p358 :001 > 3405691582.to_s(16)

139. 1.8.7-p358 :001 > 3405691582.to_s(16)
=> “cafebabe”

140. 1.8.7-p358 :001 > 3405691582.to_s(16)
=> “cafebabe”
1.8.7-p358 :002 > "cafebabe".to_i(16)

141. 1.8.7-p358 :001 > 3405691582.to_s(16)
=> “cafebabe”
1.8.7-p358 :002 > "cafebabe".to_i(16)
=> 3405691582

142. 23
flip-flop

143. 1.8.7-p358 :001 > a = [*1..100]
=> [1, 2, 3, 4, 5, 6, .., 99, 100]

144. 1.8.7-p358 :001 > a = [*1..100]
=> [1, 2, 3, 4, 5, 6, .., 99, 100]
1.8.7-p358 :002 > a.each_with_index {|x,i| p x if (i==20..i==34)}

145. 1.8.7-p358 :001 > a = [*1..100]
=> [1, 2, 3, 4, 5, 6, .., 99, 100]
1.8.7-p358 :002 > a.each_with_index {|x,i| p x if (i==20..i==34)}
21
22
...
34
35
=> [1, 2, 3, 4, 5, 6, .., 99, 100]

146. 24
0b

147. 1.8.7-p358 :001 > val = 0b11100100

148. 1.8.7-p358 :001 > val = 0b11100100
=> 228

149. 1.8.7-p358 :001 > val = 0b11100100
=> 228
1.8.7-p358 :002 > val.class

150. 1.8.7-p358 :001 > val = 0b11100100
=> 228
1.8.7-p358 :002 > val.class
=> Fixnum

151. 1.8.7-p358 :001 > val = 0b11100100
=> 228
1.8.7-p358 :002 > val.class
=> Fixnum
1.8.7-p358 :003 > val[4]

152. 1.8.7-p358 :001 > val = 0b11100100
=> 228
1.8.7-p358 :002 > val.class
=> Fixnum
1.8.7-p358 :003 > val[4]
=> 0

153. 1.8.7-p358 :001 > val = 0b11100100
=> 228
1.8.7-p358 :002 > val.class
=> Fixnum
1.8.7-p358 :003 > val[4]
=> 0
1.8.7-p358 :004 > val[5]

154. 1.8.7-p358 :001 > val = 0b11100100
=> 228
1.8.7-p358 :002 > val.class
=> Fixnum
1.8.7-p358 :003 > val[4]
=> 0
1.8.7-p358 :004 > val[5]
=> 1

155. 25
ensure and return

156. 1.8.7-p358 :001 > def foo; 0; ensure; 1; end
1.8.7-p358 :002 > foo

157. 1.8.7-p358 :001 > def foo; 0; ensure; 1; end
1.8.7-p358 :002 > foo
=> 0

158. 1.8.7-p358 :001 > def foo; 0; ensure; 1; end
1.8.7-p358 :002 > foo
=> 0
1.8.7-p358 :003 > def foo; 0; ensure; return 1; end
1.8.7-p358 :004 > foo

159. 1.8.7-p358 :001 > def foo; 0; ensure; 1; end
1.8.7-p358 :002 > foo
=> 0
1.8.7-p358 :003 > def foo; 0; ensure; return 1; end
1.8.7-p358 :004 > foo
=> 1

160. 1.8.7-p358 :001 > def foo; 0; ensure; 1; end
1.8.7-p358 :002 > foo
=> 0
1.8.7-p358 :003 > def foo; 0; ensure; return 1; end
1.8.7-p358 :004 > foo
=> 1
1.8.7-p358 :005 > def foo; return 0; ensure; 1; end
1.8.7-p358 :006 > foo

161. 1.8.7-p358 :001 > def foo; 0; ensure; 1; end
1.8.7-p358 :002 > foo
=> 0
1.8.7-p358 :003 > def foo; 0; ensure; return 1; end
1.8.7-p358 :004 > foo
=> 1
1.8.7-p358 :005 > def foo; return 0; ensure; 1; end
1.8.7-p358 :006 > foo
=> 0

162. 1.8.7-p358 :001 > def foo; 0; ensure; 1; end
1.8.7-p358 :002 > foo
=> 0
1.8.7-p358 :003 > def foo; 0; ensure; return 1; end
1.8.7-p358 :004 > foo
=> 1
1.8.7-p358 :005 > def foo; return 0; ensure; 1; end
1.8.7-p358 :006 > foo
=> 0
1.8.7-p358 :007 > def foo; return 0; ensure; return 1; end
1.8.7-p358 :006 > foo

163. 1.8.7-p358 :001 > def foo; 0; ensure; 1; end
1.8.7-p358 :002 > foo
=> 0
1.8.7-p358 :003 > def foo; 0; ensure; return 1; end
1.8.7-p358 :004 > foo
=> 1
1.8.7-p358 :005 > def foo; return 0; ensure; 1; end
1.8.7-p358 :006 > foo
=> 0
1.8.7-p358 :007 > def foo; return 0; ensure; return 1; end
1.8.7-p358 :006 > foo
=> 1

164. 26
benchmark

165. 1.8.7-p358 :001 > require ‘benchmark’
=> true

166. 1.8.7-p358 :001 > require ‘benchmark’
=> true
1.8.7-p358 :002 > n = 50000
003 > Benchmark.bm(7) do |x|
004 > x.report("for:") { for i in 1..n; a = "1"; end }
005 > x.report("times:") { n.times do ; a = "1"; end }
006 > x.report("upto:") { 1.upto(n) do ; a = "1"; end }
007 > end

167. 1.8.7-p358 :001 > require ‘benchmark’
=> true
1.8.7-p358 :002 > n = 50000
003 > Benchmark.bm(7) do |x|
004 > x.report("for:") { for i in 1..n; a = "1"; end }
005 > x.report("times:") { n.times do ; a = "1"; end }
006 > x.report("upto:") { 1.upto(n) do ; a = "1"; end }
007 > end
user system total real
for: 0.020000 0.000000 0.020000 ( 0.017378)
times: 0.010000 0.000000 0.010000 ( 0.013688)
upto: 0.020000 0.000000 0.020000 ( 0.014495)
=> true

168. 27
classes are objects

169. 1.8.7-p358 :001 > class ExceptionOne < Exception; end
=> nil

170. 1.8.7-p358 :001 > class ExceptionOne < Exception; end
=> nil
1.8.7-p358 :002 > ExceptionTwo = Class.new(Exception)
=> ExceptionTwo

171. 1.8.7-p358 :001 > class ExceptionOne < Exception; end
=> nil
1.8.7-p358 :002 > ExceptionTwo = Class.new(Exception)
=> ExceptionTwo
1.8.7-p358 :003 > raise ExceptionOne

172. 1.8.7-p358 :001 > class ExceptionOne < Exception; end
=> nil
1.8.7-p358 :002 > ExceptionTwo = Class.new(Exception)
=> ExceptionTwo
1.8.7-p358 :003 > raise ExceptionOne
ExceptionOne: ExceptionOne
! from (irb):3

173. 1.8.7-p358 :001 > class ExceptionOne < Exception; end
=> nil
1.8.7-p358 :002 > ExceptionTwo = Class.new(Exception)
=> ExceptionTwo
1.8.7-p358 :003 > raise ExceptionOne
ExceptionOne: ExceptionOne
! from (irb):3
1.8.7-p358 :004 > raise ExceptionTwo

174. 1.8.7-p358 :001 > class ExceptionOne < Exception; end
=> nil
1.8.7-p358 :002 > ExceptionTwo = Class.new(Exception)
=> ExceptionTwo
1.8.7-p358 :003 > raise ExceptionOne
ExceptionOne: ExceptionOne
! from (irb):3
1.8.7-p358 :004 > raise ExceptionTwo
ExceptionTwo: ExceptionTwo
! from (irb):4

175. 28
[].sample

176. Loading development environment (Rails 2.3.10)
>> a = [1,2,3,4,5]
=> [1,2,3,4,5]
>> a.sample

177. Loading development environment (Rails 2.3.10)
>> a = [1,2,3,4,5]
=> [1,2,3,4,5]
>> a.sample
=> 3

178. Loading development environment (Rails 2.3.10)
>> a = [1,2,3,4,5]
=> [1,2,3,4,5]
>> a.sample
=> 3
>> a.sample
=> 4

179. Loading development environment (Rails 2.3.10)
>> a = [1,2,3,4,5]
=> [1,2,3,4,5]
>> a.sample
=> 3
>> a.sample
=> 4
>> a.sample(2)

180. Loading development environment (Rails 2.3.10)
>> a = [1,2,3,4,5]
=> [1,2,3,4,5]
>> a.sample
=> 3
>> a.sample
=> 4
>> a.sample(2)
=> [4, 2]

181. rails things

182. 29
helper

183. Loading development environment (Rails 2.3.10)
>> helper.number_to_currency(100)

184. Loading development environment (Rails 2.3.10)
>> helper.number_to_currency(100)
=> "$100.00"

185. Loading development environment (Rails 2.3.10)
>> helper.number_to_currency(100)
=> "$100.00"
>> helper.number_to_human_size(1000000000000000)

186. Loading development environment (Rails 2.3.10)
>> helper.number_to_currency(100)
=> "$100.00"
>> helper.number_to_human_size(1000000000000000)
=> “909.5 TB”

187. 30
group...count

188. Loading development environment (Rails 3.0.7)
jruby-1.5.6 :001 > DataSource.group(:beta).count

189. Loading development environment (Rails 3.0.7)
jruby-1.5.6 :001 > DataSource.group(:beta).count
=> #<OrderedHash {false=>4951, true=>233}>

190. command line

191. 31
sandbox

192. $ script/console --sandbox

193. $ script/console --sandbox
Loading development environment in sandbox (Rails 2.3.10)
Any modifications you make will be rolled back on exit
NOTE: Gem.source_index is deprecated, use Specification...

194. 32
rake stats

195. $ rake stats

196. $ rake stats
+----------------------+-------+-------+---------+---------+-----+-------+
| Name | Lines | LOC | Classes | Methods | M/C | LOC/M |
+----------------------+-------+-------+---------+---------+-----+-------+
| Controllers | 4941 | 4077 | 67 | 399 | 5 | 8 |
| Helpers | 970 | 787 | 0 | 103 | 0 | 5 |
| Models | 9779 | 7878 | 163 | 989 | 6 | 5 |
| Libraries | 5932 | 4496 | 108 | 447 | 4 | 8 |
| Integration tests | 1731 | 552 | 18 | 8 | 0 | 67 |
| Functional tests | 9767 | 8248 | 52 | 90 | 1 | 89 |
| Unit tests | 16470 | 13678 | 181 | 97 | 0 | 139 |
+----------------------+-------+-------+---------+---------+-----+-------+
| Total | 49590 | 39716 | 589 | 2133 | 3 | 16 |
+----------------------+-------+-------+---------+---------+-----+-------+
Code LOC: 17238 Test LOC: 22478 Code to Test Ratio: 1:1.3

197. 33
rake notes

198. $ rake notes

199. $ rake notes
app/controllers/company_importers_controller.rb:
* [241] [TODO] refactor to raise ActiveRecord::RecordNotFound instead of nil.
app/controllers/open_id_controller.rb:
* [ 44] [TODO] refactor the below.
app/controllers/open_social_controller.rb:
* [134] [TODO] Remove this code after enough data was collected (trobrock)
app/helpers/reports_helper.rb:
* [ 12] [TODO] The core utility of these helpers could be moved into the BaseReport class
and then we can get the date ranges from the controller.
app/models/axe/outright/aggregation/aggregation_director.rb:
* [ 33] [TODO] remove this if possible - it's here b/c you get the 'expected
* [131] [TODO] why is reload necessary?
...

200. 34
rake routes

201. $ rake routes

202. $ rake routes
=> QueryTrace disabled; CTRL- to toggle
** Erubis 2.6.6
emails GET /emails(.:format) {:controller=>"emails", :action=>"index"}
POST /emails(.:format) {:controller=>"emails", :action=>"create"}
new_email GET /emails/new(.:format) {:controller=>"emails", :action=>"new"}
edit_email GET /emails/:id/edit(.:format) {:controller=>"emails", :action=>"edit"}
email GET /emails/:id(.:format) {:controller=>"emails", :action=>"show"}
PUT /emails/:id(.:format) {:controller=>"emails", :action=>"update"}
DELETE /emails/:id(.:format) {:controller=>"emails", :action=>"destroy"}
root / {:controller=>"dashboard", :action=>"root"}
dashboard /dashboard {:controller=>"dashboard", :action=>"index"}
self_identify /self_identify {:controller=>"dashboard", :action=>"self_identify"}
undo_self_identify /undo_self_identify {:controller=>"dashboard", :action=>"undo_self_identify"}
request_merchant /request_merchant {:controller=>"dashboard", :action=>"request_merchant"}
welcome /welcome {:controller=>"dashboard", :action=>"welcome"}
/companies/profit {:controller=>"companies", :action=>"profit"}
address_import_invitations GET /invitations/address_import(.:format) {:controller=>"invitations", :action=>"address_import"}
bookkeeper_client_invitations GET /invitations/bookkeeper_client(.:format) {:controller=>"invitations", :action=>"bookkeeper_client"}
invitations GET /invitations(.:format) {:controller=>"invitations", :action=>"index"}
POST /invitations(.:format) {:controller=>"invitations", :action=>"create"}
new_invitation GET /invitations/new(.:format) {:controller=>"invitations", :action=>"new"}
edit_invitation GET /invitations/:id/edit(.:format) {:controller=>"invitations", :action=>"edit"}
invitation GET /invitations/:id(.:format) {:controller=>"invitations", :action=>"show"}
PUT /invitations/:id(.:format) {:controller=>"invitations", :action=>"update"}
DELETE /invitations/:id(.:format) {:controller=>"invitations", :action=>"destroy"}
new_feedback GET /feedback/new(.:format) {:controller=>"feedback", :action=>"new"}
edit_feedback GET /feedback/edit(.:format) {:controller=>"feedback", :action=>"edit"}
feedback GET /feedback(.:format) {:controller=>"feedback", :action=>"show"}
PUT /feedback(.:format) {:controller=>"feedback", :action=>"update"}
DELETE /feedback(.:format) {:controller=>"feedback", :action=>"destroy"}
POST /feedback(.:format) {:controller=>"feedback", :action=>"create"}
visible_accounts GET /visible_accounts(.:format) {:controller=>"visible_accounts", :action=>"index"}
/tax_calendar {:controller=>"redirect", :action=>"to_outright"}
...

203. 35
syntax check

204. $ ruby -c app/models/email_campaign.rb

205. $ ruby -c app/models/email_campaign.rb
Syntax OK

206. $ ruby -c app/models/email_campaign.rb
Syntax OK
$ ruby -c app/models/axe/outright/filter_chain.rb

207. $ ruby -c app/models/email_campaign.rb
Syntax OK
$ ruby -c app/models/axe/outright/filter_chain.rb
app/models/axe/outright/filter_chain.rb:36: syntax error, unexpected
$end, expecting kEND

208. 36
.irbrc

209. $ vim ~/.irbrc

210. $ vim ~/.irbrc
require "rubygems"
require "wirble"
Wirble.init
Wirble.colorize
colors = Wirble::Colorize.colors.merge({
:comma => :green,
:refers => :green,
})
Wirble::Colorize.colors = colors
class Object
def own_methods
(self.methods - Object.new.methods).sort
end
end