Apparently some modules are not updated for the exception
 NotImplementedError 

pigeon% ruby -rdelegate -ve 'Delegator.new(12).to_s'
ruby 1.8.0 (2003-03-23) [i686-linux]
-e:1: uninitialized constant NotImplementError at Delegator (NameError)
pigeon% 

pigeon% find . -name '*.rb' -print | xargs grep NotImplementError
./ext/tk/lib/tk.rb:    raise NotImplementError, "need to define `__conf_cmd'"
./ext/tk/lib/tk.rb:    raise NotImplementError, "need to define `__item_pathname'"
./lib/delegate.rb:    raise NotImplementError, "need to define `__getobj__'"
./lib/irb/input-method.rb:      IRB.fail NotImplementError, "gets"
./lib/irb/lc/ja/error.rb:  def_exception :NotImplementError, '`%s\'B$NDj5A$,I,MW$G$9'
./lib/irb/lc/error.rb:  def_exception :NotImplementError, "Need to define `%s'"
./lib/racc/parser.rb:  NotImplementedError = NotImplementError
pigeon% 



Guy Decoux