Enumerable nil

enumerable_nil.txt

$ rails c
nLoading development environment (Rails 3.2.1)

1.9.3p0 :001 > nil
 => nil 

1.9.3p0 :002 > nil.nil?
 => true 

1.9.3p0 :004 > nil.each
NoMethodError: undefined method `each' for nil:NilClass
	from (irb):4
	from /Users/mamiano/.rvm/gems/ruby-1.9.3-p0@checkie/gems/railties-3.2.1/lib/rails/commands/console.rb:47:in `start'
	from /Users/mamiano/.rvm/gems/ruby-1.9.3-p0@checkie/gems/railties-3.2.1/lib/rails/commands/console.rb:8:in `start'
	from /Users/mamiano/.rvm/gems/ruby-1.9.3-p0@checkie/gems/railties-3.2.1/lib/rails/commands.rb:41:in `<top (required)>'
	from script/rails:6:in `require'
	from script/rails:6:in `<main>'

1.9.3p0 :006 >   def nil.each
1.9.3p0 :007?>   end
 => nil 

1.9.3p0 :008 > nil.each { |f| puts f}
 => nil 

1.9.3p0 :009 > class NilClass
1.9.3p0 :010?>   include Enumerable
1.9.3p0 :011?>   def each ; end
1.9.3p0 :012?>   def to_a; []; end
1.9.3p0 :013?>   end
 => nil 

1.9.3p0 :014 > nil.each
 => nil 

1.9.3p0 :015 > nil.to_a
 => [] 

1.9.3p0 :016 > nil.map
 => #<Enumerator: nil:map> 

1.9.3p0 :017 > nil.map { |n| n }
 => [] 

1.9.3p0 :018 > nil.any? { |n| n.nil? }
 => false 

1.9.3p0 :019 > quit