1 files changed, 17 insertions, 14 deletions

diff --git a/railties/lib/rails/generators/base.rb b/railties/lib/rails/generators/base.rb
index 60e94486bb..1648b9674a 100644
--- a/railties/lib/rails/generators/base.rb
+++ b/railties/lib/rails/generators/base.rb
@@ -31,10 +31,9 @@ module Rails
       # root otherwise uses a default description.
       def self.desc(description=nil)
         return super if description
-        usage = source_root && File.expand_path("../USAGE", source_root)
 
-        @desc ||= if usage && File.exist?(usage)
-          ERB.new(File.read(usage)).result(binding)
+        @desc ||= if usage_path
+          ERB.new(File.read(usage_path)).result(binding)
         else
           "Description:\n    Create #{base_name.humanize.downcase} files for #{generator_name} generator."
         end
@@ -213,7 +212,8 @@ module Rails
       # root, you should use source_root.
       def self.default_source_root
         return unless base_name && generator_name
-        path = File.expand_path(File.join(base_name, generator_name, 'templates'), base_root)
+        return unless default_generator_root
+        path = File.join(default_generator_root, 'templates')
         path if File.exists?(path)
       end
 
@@ -248,7 +248,6 @@ module Rails
 
         # Check whether the given class names are already taken by user
         # application or Ruby on Rails.
-        #
         def class_collisions(*class_names) #:nodoc:
           return unless behavior == :invoke
 
@@ -275,13 +274,11 @@ module Rails
         end
 
         # Use Rails default banner.
-        #
         def self.banner
           "rails generate #{namespace.sub(/^rails:/,'')} #{self.arguments.map{ |a| a.usage }.join(' ')} [options]".gsub(/\s+/, ' ')
         end
 
         # Sets the base_name taking into account the current class namespace.
-        #
         def self.base_name
           @base_name ||= begin
             if base = name.to_s.split('::').first
@@ -292,7 +289,6 @@ module Rails
 
         # Removes the namespaces and get the generator name. For example,
         # Rails::Generators::ModelGenerator will return "model" as generator name.
-        #
         def self.generator_name
           @generator_name ||= begin
             if generator = name.to_s.split('::').last
@@ -304,20 +300,17 @@ module Rails
 
         # Return the default value for the option name given doing a lookup in
         # Rails::Generators.options.
-        #
         def self.default_value_for_option(name, options)
           default_for_option(Rails::Generators.options, name, options, options[:default])
         end
 
         # Return default aliases for the option name given doing a lookup in
         # Rails::Generators.aliases.
-        #
         def self.default_aliases_for_option(name, options)
           default_for_option(Rails::Generators.aliases, name, options, options[:aliases])
         end
 
         # Return default for the option name given doing a lookup in config.
-        #
         def self.default_for_option(config, name, options, default)
           if generator_name and c = config[generator_name.to_sym] and c.key?(name)
             c[name]
@@ -331,14 +324,12 @@ module Rails
         end
 
         # Keep hooks configuration that are used on prepare_for_invocation.
-        #
         def self.hooks #:nodoc:
           @hooks ||= from_superclass(:hooks, {})
         end
 
         # Prepare class invocation to search on Rails namespace if a previous
         # added hook is being used.
-        #
         def self.prepare_for_invocation(name, value) #:nodoc:
           return super unless value.is_a?(String) || value.is_a?(Symbol)
 
@@ -354,7 +345,6 @@ module Rails
 
         # Small macro to add ruby as an option to the generator with proper
         # default value plus an instance helper method called shebang.
-        #
         def self.add_shebang_option!
           class_option :ruby, :type => :string, :aliases => "-r", :default => Thor::Util.ruby_command,
                               :desc => "Path to the Ruby binary of your choice", :banner => "PATH"
@@ -373,6 +363,19 @@ module Rails
           }
         end
 
+        def self.usage_path
+          paths = [
+            source_root && File.expand_path("../USAGE", source_root),
+            default_generator_root && File.join(default_generator_root, "USAGE")
+          ]
+          paths.compact.detect { |path| File.exists? path }
+        end
+
+        def self.default_generator_root
+          path = File.expand_path(File.join(base_name, generator_name), base_root)
+          path if File.exists?(path)
+        end
+
     end
   end
 end