mongo_mapper's gem fix

fix_rails3b4_ruby192rc2.diff

From 9bed12e78880a4ddce90ca4a846090773bc8538d Mon Sep 17 00:00:00 2001
From: Dmitrii Samoilov <germaninthetown@gmail.com>
Date: Tue, 20 Jul 2010 11:10:51 +0300
Subject: [PATCH] fix for the bug in plugins.rb (const_defined?(:ClassMethods) for whatever reason doesn't work for rails3b4 and ruby1.9.2-rc2)

---
 lib/mongo_mapper/plugins.rb |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/lib/mongo_mapper/plugins.rb b/lib/mongo_mapper/plugins.rb
index eba99b6..fc39187 100644
--- a/lib/mongo_mapper/plugins.rb
+++ b/lib/mongo_mapper/plugins.rb
@@ -6,7 +6,9 @@ module MongoMapper
     end
 
     def plugin(mod)
-      extend mod::ClassMethods     if mod.const_defined?(:ClassMethods)
+      # for whatever reason mod.const_defined?(:ClassMethods) doesn't work in ruby192rc2+rails3b4 hence this workaround
+      extend mod::ClassMethods     if mod.constants.include?(:ClassMethods)
+
       include mod::InstanceMethods if mod.const_defined?(:InstanceMethods)
       mod.configure(self)          if mod.respond_to?(:configure)
       plugins << mod
-- 
1.5.6.3