Only the timeout method should be public on the Timeout module

lib/timeout.rb

@@ -133,6 +133,7 @@ def self.ensure_timeout_thread_created
       end
     end
   end
+  private_class_method :ensure_timeout_thread_created
 
   # We keep a private reference so that time mocking libraries won't break
   # Timeout.
@@ -167,7 +168,7 @@ def self.ensure_timeout_thread_created
   # Note that this is both a method of module Timeout, so you can <tt>include
   # Timeout</tt> into your classes so they have a #timeout method, as well as
   # a module method, so you can call it directly as Timeout.timeout().
-  def timeout(sec, klass = nil, message = nil, &block)   #:yield: +sec+
+  def self.timeout(sec, klass = nil, message = nil, &block)   #:yield: +sec+
     return yield(sec) if sec == nil or sec.zero?
     raise ArgumentError, "Timeout sec must be a non-negative number" if 0 > sec
 
@@ -177,7 +178,7 @@ def timeout(sec, klass = nil, message = nil, &block)   #:yield: +sec+
       return scheduler.timeout_after(sec, klass || Error, message, &block)
     end
 
-    Timeout.ensure_timeout_thread_created
+    ensure_timeout_thread_created
     perform = Proc.new do |exc|
       request = Request.new(Thread.current, sec, exc, message)
       QUEUE_MUTEX.synchronize do
@@ -197,5 +198,8 @@ def timeout(sec, klass = nil, message = nil, &block)   #:yield: +sec+
       Error.handle_timeout(message, &perform)
     end
   end
-  module_function :timeout
+
+  private def timeout(*args, &block)
+    Timeout.timeout(*args, &block)
+  end
 end

test/test_timeout.rb

@@ -4,6 +4,12 @@
 
 class TestTimeout < Test::Unit::TestCase
 
+  def test_public_methods
+    assert_equal [:timeout], Timeout.private_instance_methods(false)
+    assert_equal [], Timeout.public_instance_methods(false)
+    assert_equal [:timeout], Timeout.singleton_class.public_instance_methods(false)
+  end
+
   def test_work_is_done_in_same_thread_as_caller
     assert_equal Thread.current, Timeout.timeout(10){ Thread.current }
   end