Make the generator skip a file if it already exists and is identical to the new file.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@2493 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

railties/CHANGELOG

 *SVN*
 
+* Make the generator skip a file if it already exists and is identical to the new file.
+
 * Add experimental plugin support #2335
 
 * Made Rakefile aware of new .js files in script.aculo.us [Thomas Fuchs]

railties/lib/rails_generator/commands.rb

@@ -146,11 +146,13 @@ def class_collisions(*class_names)
         # the user what to do.
         def file(relative_source, relative_destination, file_options = {})
           # Determine full paths for source and destination files.
-          source      = source_path(relative_source)
-          destination = destination_path(relative_destination)
+          source              = source_path(relative_source)
+          destination         = destination_path(relative_destination)
+          destination_exists  = File.exists?(destination)
+          return logger.identical(relative_destination) if destination_exists and identical?(source, destination)
 
           # Check for and resolve file collisions.
-          if File.exists?(destination)
+          if destination_exists
 
             # Make a choice whether to overwrite the file.  :force and
             # :skip already have their mind made up, but give :ask a shot.
@@ -207,6 +209,11 @@ def file(relative_source, relative_destination, file_options = {})
           system("svn add #{destination}") if options[:svn]
         end
 
+        # Checks if the source and the destination file are identical.
+        def identical?(source, destination)
+          IO.read(source) == IO.read(destination)
+        end
+
         # Generate a file for a Rails application using an ERuby template.
         # Looks up and evalutes a template by name and writes the result.
         #