1 files changed, 83 insertions, 0 deletions
diff --git a/railties/lib/rails/plugin.rb b/railties/lib/rails/plugin.rb
new file mode 100644
index 0000000000..2feb90bf14
--- /dev/null
+++ b/railties/lib/rails/plugin.rb
@@ -0,0 +1,83 @@
+module Rails
+
+  # The Plugin class should be an object which provides the following methods:
+  #
+  # * +name+       - used during initialisation to order the plugin (based on name and
+  #                  the contents of <tt>config.plugins</tt>)
+  # * +valid?+     - returns true if this plugin can be loaded
+  # * +load_paths+ - each path within the returned array will be added to the $LOAD_PATH
+  # * +load+       - finally 'load' the plugin.
+  #
+  # These methods are expected by the Rails::Plugin::Locator and Rails::Plugin::Loader classes.
+  # The default implementation returns the <tt>lib</tt> directory as its </tt>load_paths</tt>, 
+  # and evaluates <tt>init.rb</tt> when <tt>load</tt> is called.
+  class Plugin
+    include Comparable
+    
+    attr_reader :directory, :name
+    
+    def initialize(directory)
+      @directory = directory
+      @name = File.basename(@directory) rescue nil
+      @loaded = false
+    end
+    
+    def valid?
+      File.directory?(directory) && (has_lib_directory? || has_init_file?)
+    end
+  
+    # Returns a list of paths this plugin wishes to make available in $LOAD_PATH
+    def load_paths
+      report_nonexistant_or_empty_plugin! unless valid?
+      has_lib_directory? ? [lib_path] : []
+    end
+
+    # Evaluates a plugin's init.rb file
+    def load(initializer)
+      report_nonexistant_or_empty_plugin! unless valid?
+      evaluate_init_rb(initializer)
+      @loaded = true
+    end
+    
+    def loaded?
+      @loaded
+    end
+    
+    def <=>(other_plugin)
+      name <=> other_plugin.name
+    end
+    
+    private
+
+      def report_nonexistant_or_empty_plugin!
+        raise LoadError, "Can not find the plugin named: #{name}"
+      end      
+    
+      def lib_path
+        File.join(directory, 'lib')
+      end
+
+      def init_path
+        File.join(directory, 'init.rb')
+      end
+
+      def has_lib_directory?
+        File.directory?(lib_path)
+      end
+
+      def has_init_file?
+        File.file?(init_path)
+      end
+
+      def evaluate_init_rb(initializer)
+         if has_init_file?
+           silence_warnings do
+             # Allow plugins to reference the current configuration object
+             config = initializer.configuration
+             
+             eval(IO.read(init_path), binding, init_path)
+           end
+         end
+      end               
+  end
+end
+\ No newline at end of file