trick.rb

# DATA, __END__,   pos
# http://shifteleven.com/articles/2009/02/09/useless-ruby-tricks-data-and-__end__
# http://stackoverflow.com/questions/1333720/ruby-scope-of-data-after-end

# You could lambda in when
case n
when lambda(&:even?)
  puts "This number is even."
...

# assoc
s1 = [ "colors", "red", "blue", "green" ]
s2 = [ "letters", "a", "b", "c" ]
s3 = "foo"
a  = [ s1, s2, s3 ]
a.assoc("letters")  #=> [ "letters", "a", "b", "c" ]
a.assoc("foo")      #=> nil

# rindex
a = [ "a", "b", "b", "b", "c" ]
a.rindex("b")        #=> 3
a.rindex("z")        #=> nil
a.rindex{|x|x=="b"}  #=> 3

# partition
(1..6).partition {|v| v.even? }  #=> [[2, 4, 6], [1, 3, 5]]

# flat_map
[[1,2],[3,4]].flat_map {|i| i }   #=> [1, 2, 3, 4]

# each_with_object
%w(foo bar).each_with_object({}) { |str, hsh| hsh[str] = str.upcase }
# => {'foo' => 'FOO', 'bar' => 'BAR'}

# drop
a = [1, 2, 3, 4, 5, 0]
a.drop(3)             #=> [4, 5, 0]