Added new generator framework that informs about its doings on generation and enables updating and destruction of generated artifacts. See the new script/destroy and script/update for more details #487 [bitsweat]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@518 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

1 files changed, 53 insertions, 0 deletions

diff --git a/railties/lib/rails_generator/manifest.rb b/railties/lib/rails_generator/manifest.rb
new file mode 100644
index 0000000000..702effa76f
--- /dev/null
+++ b/railties/lib/rails_generator/manifest.rb
@@ -0,0 +1,53 @@
+module Rails
+  module Generator
+
+    # Manifest captures the actions a generator performs.  Instantiate
+    # a manifest with an optional target object, hammer it with actions,
+    # then replay or rewind on the object of your choice.
+    #
+    # Example:
+    #   manifest = Manifest.new { |m|
+    #     m.make_directory '/foo'
+    #     m.create_file '/foo/bar.txt'
+    #   }
+    #   manifest.replay(creator)
+    #   manifest.rewind(destroyer)
+    class Manifest
+      attr_reader :target
+
+      # Take a default action target.  Yield self if block given.
+      def initialize(target = nil)
+        @target, @actions = target, []
+        yield self if block_given?
+      end
+
+      # Record an action.
+      def method_missing(action, *args, &block)
+        @actions << [action, args, block]
+      end
+
+      # Replay recorded actions.
+      def replay(target = nil)
+        send_actions(target || @target, @actions)
+      end
+
+      # Rewind recorded actions.
+      def rewind(target = nil)
+        send_actions(target || @target, @actions.reverse)
+      end
+
+      # Erase recorded actions.
+      def erase
+        @actions = []
+      end
+
+      private
+        def send_actions(target, actions)
+          actions.each do |method, args, block|
+            target.send(method, *args, &block)
+          end
+        end
+    end
+
+  end
+end