Vidul Nikolaev Petrov » basis http://www.vidul.com my web space Thu, 09 Sep 2010 22:51:55 +0000 http://wordpress.org/?v=2.9.2 en hourly 1 How false Is nil http://www.vidul.com/2008/08/04/how-false-is-nil/ http://www.vidul.com/2008/08/04/how-false-is-nil/#comments Mon, 04 Aug 2008 14:59:00 +0000 Vidul urn:uuid:{a.guid} Use nil when the return is a boolean value.
Use false when the return is either false or not true object.
Otherwise they have pretty much the same semantic:

nil == false => false
nil.nil?        => true
false.nil?     => false
true.nil?      => false
 
if !nil && !false
  puts 'true'
end
 
if nil.nil? && !true.nil?
  puts 'true'
end
 
>> TrueClass.ancestors
=> [TrueClass, Object, Kernel]
>> FalseClass.ancestors
=> [FalseClass, Object, Kernel]
>> NilClass.ancestors
=> [NilClass, Object, Kernel]

Ruby core docs

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