Add Jekyll::Deprecator

lib/jekyll/deprecator.rb

@@ -0,0 +1,25 @@
+module Jekyll
+  class Deprecator
+    def self.process(args)
+      deprecation_message args, "--server", "The --server command has been replaced by the \
+                          'serve' subcommand."
+      deprecation_message args, "--no-server", "To build Jekyll without launching a server, \
+                          use the 'build' subcommand."
+      deprecation_message args, "--auto", "The switch '--auto' has been replaced with '--watch'."
+      deprecation_message args, "--no-auto", "To disable auto-replication, simply leave off \
+                          the '--watch' switch."
+      deprecation_message args, "--pygments", "The 'pygments' setting can only be set in \
+                          your config files."
+      deprecation_message args, "--paginate", "The 'paginate' setting can only be set in your \
+                          config files."
+      deprecation_message args, "--url", "The 'url' setting can only be set in your config files."
+    end
+
+    def self.deprecation_message(args, deprecated_argument, message)
+      if args.include?(deprecated_argument)
+        Jekyll.warn "Deprecation:", message
+        exit(1)
+      end
+    end
+  end
+end