Add convenience method to find out if instance is live.

README.md

@@ -171,6 +171,13 @@ Finally, if you got an item by reifying one of its versions, you can navigate ba
     >> widget = latest_version.reify
     >> widget.version == latest_version    # true
 
+You can find out whether a model instance is the current, live one -- or whether it came instead from a previous version -- with `live?`:
+
+    >> widget = Widget.find 42
+    >> widget.live?                        # true
+    >> widget = widget.versions.last.reify
+    >> widget.live?                        # false
+
 
 ## Finding Out Who Was Responsible For A Change
 

lib/paper_trail/has_paper_trail.rb

@@ -78,6 +78,12 @@ module PaperTrail
         end
       end
 
+      # Returns true if this instance is the current, live one;
+      # returns false if this instance came from a previous version.
+      def live?
+        version.nil?
+      end
+
       # Returns who put the object into its current state.
       def originator
         versions.last.try :whodunnit

test/paper_trail_model_test.rb

@@ -46,8 +46,7 @@ end
 
 class HasPaperTrailModelTest < Test::Unit::TestCase
   load_schema
-=begin
-=end
+
   context 'A record' do
     setup { @article = Article.create }
 
@@ -70,6 +69,10 @@ class HasPaperTrailModelTest < Test::Unit::TestCase
       assert_equal [], @widget.versions
     end
 
+    should 'be live' do
+      assert @widget.live?
+    end
+
 
     context 'which is then created' do
       setup { @widget.update_attributes :name => 'Henry' }
@@ -87,6 +90,10 @@ class HasPaperTrailModelTest < Test::Unit::TestCase
         assert_match /create/i, @widget.versions.first.event
       end
 
+      should 'be live' do
+        assert @widget.live?
+      end
+
 
       context 'and then updated without any changes' do
         setup { @widget.save }
@@ -120,6 +127,10 @@ class HasPaperTrailModelTest < Test::Unit::TestCase
           assert_match /update/i, @widget.versions.last.event
         end
 
+        should 'have versions that are not live' do
+          assert @widget.versions.map(&:reify).compact.all? { |w| !w.live? }
+        end
+
 
         context 'and has one associated object' do
           setup do