Module and class hierarchy : inheritance « Class « Ruby






  1. Ruby
  2. Class
  3. inheritance

Module and class hierarchy


module A
end                 # Empty module
module B 
   include A 
end                 # Module B includes A

class C 
   include B 
end                 # Class C includes module B

puts C < B               # => true: C includes B
puts B < A               # => true: B includes A
puts C < A               # => true
puts Fixnum < Integer    # => true: all fixnums are integers
puts Integer <Comparable # => true: integers are comparable
puts Integer < Fixnum    # => false: not all integers are fixnums
puts String < Numeric    # => nil: strings are not numbers

puts A.ancestors         # => [A]
puts B.ancestors         # => [B, A]
puts C.ancestors         # => [C, B, A, Object, Kernel]
puts String.ancestors    # => [String, Enumerable, Comparable, Object, Kernel]
                    # Note: in Ruby 1.9 String is no longer Enumerable

puts C.include?(B)       # => true
puts C.include?(A)       # => true
puts B.include?(A)       # => true
puts A.include?(A)       # => false
puts A.include?(B)       # => false

puts A.included_modules  # => []
puts B.included_modules  # => [A]
puts C.included_modules  # => [B, A, Kernel]








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