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Bug #9413

closed

Object Metaclass Constants Array doesn't Include Singleton Constant

Added by demisx (Dmitri Moore) about 10 years ago. Updated about 10 years ago.

Status:
Closed
Assignee:
-
Target version:
ruby -v:
ruby 2.1.0p0 (2013-12-25 revision 44422) [x86_64-darwin12.0]
[ruby-core:<unknown>]

Description

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

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