Bug #9413: Object Metaclass Constants Array doesn't Include Singleton Constant

• Status: Closed
• Assignee: -
• Target version: 2.2.0
• ruby -v: ruby 2.1.0p0 (2013-12-25 revision 44422) [x86_64-darwin12.0]
• Backport: 1.9.3: DONE, 2.0.0: DONE, 2.1: DONE

[demisx (Dmitri Moore)]

Let's assume we have this Ruby class:

class MyClass
  class << self
    MC_CONST = 30
  end
end 

Then, let's instantiate MyClass and add another constant to the object's metaclass:

m = MyClass.new
class << m
  OBJ_MC_CONST = 50
end

There are no issues with the object singleton constant:

m.singleton_class::OBJ_MC_CONST # => 50 <-- [OK]
m.singleton_class.constants.include? :OBJ_MC_CONST # => true <- [OK]

But not exactly what I'd expect with the class singleton constant:

MyClass.singleton_class::MC_CONST # => 30 <-- [OK]
MyClass.singleton_class.const_get :MC_CONST # => 30 <-- [OK]
MyClass.singleton_class.const_defined? :MC_CONST=> true <-- [OK]
MyClass.singleton_class.constants.include? :MC_CONST # => false <-- [Why???]

Why does the array returned by .constants method on metaclass of MyClass class doesn't contain :MC_CONST?

Here is the SO (StackOverflow) thread for this http://stackoverflow.com/questions/21057002/where-are-the-ruby-class-singleton-constants-stored/21061117?iemail=1&noredirect=1#21061117

[nobu (Nobuyoshi Nakada)]

• Backport changed from 1.9.3: UNKNOWN, 2.0.0: UNKNOWN, 2.1: UNKNOWN to 1.9.3: REQUIRED, 2.0.0: REQUIRED, 2.1: REQUIRED

[nobu (Nobuyoshi Nakada)]

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

Applied in changeset r44628.

---

eval.c: singleton class constants

• eval.c (rb_mod_s_constants): return its own constants for other
  than Module itself. [ruby-core:59763] [Bug #9413]

[usa (Usaku NAKAMURA)]

• Backport changed from 1.9.3: REQUIRED, 2.0.0: REQUIRED, 2.1: REQUIRED to 1.9.3: DONE, 2.0.0: REQUIRED, 2.1: REQUIRED

backported into ruby_1_9_3 at r44939.

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 1.9.3: DONE, 2.0.0: REQUIRED, 2.1: REQUIRED to 1.9.3: DONE, 2.0.0: DONE, 2.1: REQUIRED

r44628 was backported to ruby_2_0_0 at r45010.

[naruse (Yui NARUSE)]

• Backport changed from 1.9.3: DONE, 2.0.0: DONE, 2.1: REQUIRED to 1.9.3: DONE, 2.0.0: DONE, 2.1: DONE

ruby_2_1 r45124 merged revision(s) 44628.