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Test script:

class Object
# good old eigenclass accessor
def eigenclass; class << self; self; end; end
end

class A; end
class B < A; end
b = B.new

p "super of eigen of b: #{b.eigenclass.superclass}"
p "super of eigen of B: #{B.eigenclass.superclass}"
p "super of eigen of A: #{A.eigenclass.superclass}"

Ruby 1.8.2 and Ruby 1.9 give the same result:

MacNusco:/usr/bin nusco$ ruby -v /strange.rb
ruby 1.8.2 (2004-12-25) [universal-darwin8.0]
"super of eigen of b: B"
"super of eigen of B: #<Class:A>"
"super of eigen of A: #<Class:Object>"

This is what I expected, and consistent with the way method lookup
works for singleton methods in both objects and classes. On the other
hand, Ruby 1.8.5 and 1.8.6 surprised me:

MacNusco:/ nusco$ ruby -v /strange.rb
ruby 1.8.6 (2007-03-13 patchlevel 0) [i686-darwin8.9.1]
"super of eigen of b: #<Class:B>"
"super of eigen of B: #<Class:Class>"
"super of eigen of A: #<Class:Class>"

What the heck?


Paolo Perrotta
Bologna, Italy