Feature #8035: singleton class should be included in ancestors

• Status: Closed
• Assignee: matz (Yukihiro Matsumoto)
• Target version: 2.1.0

[marcandre (Marc-Andre Lafortune)]

I feel it would be consistent if:

k.ancestors.include?(k) #=> always true if k.is_a?(Class)

This is currently the case except for singleton classes:

class << ""; include Enumerable; end.ancestors
# => [Enumerable, String, Comparable, Object, Kernel, BasicObject]
# would be more consistent:
# => [#<Class:#<String:0x0000010113d268>>, Enumerable, String, Comparable, Object, Kernel, BasicObject]

Note that the singleton classes do appear in the ancestors if a module is instead prepended:

class << ""; prepend Enumerable; end.ancestors
# => [Enumerable, #<Class:#<String:0x0000010113d268>>, String, Comparable, Object, Kernel, BasicObject]

Thanks

[alexeymuranov (Alexey Muranov)]

Singleton class it the same thing as metaclass, right? I feel it would be better to keep it invisible, and maybe in the future to remove it completely and to allow objects to keep their singleton methods themselves.

[matz (Yukihiro Matsumoto)]

Agreed. I will accept it unless any other compatibility problem raises.

Matz.

[marcandre (Marc-Andre Lafortune)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

This issue was solved with changeset r39628.
Marc-Andre, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• class.c (rb_mod_ancestors): Include singleton_class in ancestors list
  [Feature #8035]

• test/ruby/test_module.rb (class): test for above

• test/ruby/marshaltestlib.rb (module): adapt test

• NEWS: list change