r: use resource

Formula/r.rb

@@ -1,12 +1,5 @@
 require 'formula'
 
-class RBashCompletion < Formula
-  # This is the same script that Debian packages use.
-  url 'http://rcompletion.googlecode.com/svn-history/r28/trunk/bash_completion/R', :using => :curl
-  version 'r28'
-  sha1 'af734b8624b33f2245bf88d6782bea0dc5d829a4'
-end
-
 class R < Formula
   homepage 'http://www.r-project.org'
   url 'http://cran.r-project.org/src/base/R-3/R-3.0.1.tar.gz'
@@ -26,6 +19,13 @@ class R < Formula
   depends_on 'valgrind' => :optional
   depends_on 'homebrew/science/openblas' if build.with? 'openblas'
 
+  # This is the same script that Debian packages use.
+  resource 'completion' do
+    url 'http://rcompletion.googlecode.com/svn-history/r28/trunk/bash_completion/R', :using => :curl
+    version 'r28'
+    sha1 'af734b8624b33f2245bf88d6782bea0dc5d829a4'
+  end
+
   def install
     args = [
       "--prefix=#{prefix}",
@@ -60,7 +60,7 @@ class R < Formula
     ln_s prefix+"R.framework/Resources/man1/R.1", man1
     ln_s prefix+"R.framework/Resources/man1/Rscript.1", man1
 
-    RBashCompletion.new.brew { bash_completion.install 'R' }
+    bash_completion.install resource('completion')
 
     prefix.install 'make-check.log' if build.include? 'test'
   end