support provider subsitution in urls

Readme.md

@@ -17,6 +17,11 @@ Usage
 
     # app/helpers/application_helper.rb
     def add_this(options)
+      # add google analytics tracking
+      url = request.request_uri
+      url += url.include?('?') ? '&' : '?'
+      url += 'utm_source=add_this&utm_medium=%{provider}'
+
       StaticAddthis.icons(options.reverse_merge(
         :title => @page_title,
         :url => request.request_uri,

lib/static_addthis.rb

@@ -22,7 +22,8 @@ def self.social_icon(provider, options={})
   end
 
   def self.link_to_provider(name, options)
-    url = CGI.escape(options[:url] || raise('addthis needs :url'))
+    url = options[:url] || raise('addthis needs :url')
+    url = CGI.escape(url.gsub('%{provider}', name))
     title = CGI.escape(options[:title] || raise('addthis needs :title'))
     username = options[:username] || raise('addthis needs :username')
     uid = options[:uid] || raise('addthis needs :uid')

spec/static_addthis_spec.rb

@@ -17,6 +17,10 @@
       StaticAddthis.icons(defaults.merge(:providers => ['Twitter'])).should include(">Twitter<")
     end
 
+    it "overwrites %{provider} in url" do
+      StaticAddthis.icons(defaults.merge(:providers => ['Twitter'], :url => 'xxx%{provider}yyy')).should include("xxxTwitteryyy")
+    end
+
     it "ignores unknown providers so i can gsub them" do
       result = StaticAddthis.icons(defaults.merge(:providers => ['Foo']))
       result.should_not include(">Foo<")