From: Kevin Howe <kh@...>
Date: 2005-02-13T06:04:59+09:00
Subject: const_defined? and inheritance

It seems that const_defined? doesnt search it's superclass:

  class A
    FOO = 'BAR'
  end

  class B < A; end

  puts A.const_get(:FOO) # => 'BAR'
  puts A.const_defined?(:FOO) # => true
  puts B.const_get(:FOO) # => 'BAR'
  puts B.const_defined?(:FOO) # => false

I had expected B.const_defined?(:FOO) to be true. Seems strange that
const_get does the lookup while const_defined? doesn't. Is there a reason
for this behaviour?

The following takes care of it:

  class A
    def self.const_defined?(symbol) super ||
superclass.const_defined?(symbol) end
  end

But would like to know why this is.

Regards,
Kevin