Issue #11064 has been updated by matz (Yukihiro Matsumoto). @sawa Singleton classes are in principle only accessed using the `singleton_class` method or the singleton class notation. Implementation wise, FL_SINGLETON is set for singleton classes. Neither is true for NilClass (nor FalseClass nor TrueClass). Matz. ---------------------------------------- Bug #11064: #singleton_methods for objects with special singleton_class returns an empty array https://bugs.ruby-lang.org/issues/11064#change-100763 * Author: rbjl (Jan Lelis) * Status: Open * Priority: Normal * ruby -v: ruby 2.2.1p85 (2015-02-26 revision 49769) [x86_64-linux] * Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN ---------------------------------------- ~~~ def nil.bla 42 end # works nil.bla #=> 42 nil.singleton_method(:bla) #=> #<Method: NilClass#bla> NilClass.instance_methods.include? :bla #=> true # does not work nil.singleton_methods #=> [] ~~~ -- https://bugs.ruby-lang.org/