https://groups.google.com/forum/#!topic/rubyonrails-core/PjGUK72BmFA

const_missing_experiment.rb

class Module
  def const_missing(const_name)
    puts "[ModuleConstMissing] #{self} missing #{const_name}"
  end
end

class FakeDelegator < BasicObject
  def self.const_missing(name)
    puts "[FakeDelegator] missing #{name}"
    if ::Object.const_defined?(name)
      ::Object.const_get(name)
    else
      super if defined?(super)
    end
  end
end

class MyObject1
  File
  NoSuch
end

puts

class MyObject2 < FakeDelegator
  File
  NoSuch
end

const_missing_experiment_output.txt

[ModuleConstMissing] MyObject1 missing NoSuch

[FakeDelegator] missing File
[FakeDelegator] missing NoSuch
[ModuleConstMissing] MyObject2 missing NoSuch