Move require_library_or_gem out of AR's abstract_adapter and into ActiveSupport. closes #1992

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@2490 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

2 files changed, 24 insertions, 0 deletions

diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index cf8b935be1..630c8bdae9 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Moved require_library_or_gem into Kernel. #1992 [Michael Schuerig <michael@schuerig.de>]
+
 * Add :rfc822 as an option for Time#to_s (to get rfc822-formatted times)
 
 * Chain the const_missing hook to any previously existing hook so rails can play nicely with rake
diff --git a/activesupport/lib/active_support/core_ext/kernel.rb b/activesupport/lib/active_support/core_ext/kernel.rb
index 54979c1a1a..168c9cddd3 100644
--- a/activesupport/lib/active_support/core_ext/kernel.rb
+++ b/activesupport/lib/active_support/core_ext/kernel.rb
@@ -28,4 +28,26 @@ module Kernel
   ensure
     $VERBOSE = old_verbose
   end
+
+  # Method that requires a library, ensuring that rubygems is loaded
+  def require_library_or_gem(library_name)
+    begin
+      require library_name
+    rescue LoadError => cannot_require
+      # 1. Requiring the module is unsuccessful, maybe it's a gem and nobody required rubygems yet. Try.
+      begin
+        require 'rubygems'
+      rescue LoadError => rubygems_not_installed
+        raise cannot_require
+      end
+      # 2. Rubygems is installed and loaded. Try to load the library again
+      begin
+        require library_name
+      rescue LoadError => gem_not_installed
+        raise cannot_require
+      end
+    end
+  end
+
+
 end