visitor.rb in build-tool-0.6.0.rc1

- old
+ new

@@ -1,10 +1,13 @@
+# -*- coding: UTF-8 -*-
+
 module MJ;
 
     class Visitable
 
         def accept( visitor )
+            raise "#{visitor.class} is not a visitable class" if visitor.instance_of? VisitorBase
             method_name = nil
             klass = self.class.ancestors.find do |ancestor|
                 method_name = "visit_#{ancestor.name.split('::')[-1]}"
                 visitor.respond_to?( method_name )
             end
@@ -16,6 +19,25 @@
             end
         end
 
     end
 
+
+    # Base class for all Visitors.
+    class VisitorBase
+
+        # The configuration object to fill with our parse results.
+        attr_reader :configuration
+
+        class ArgumentsError < StandardError
+        end
+
+        def initialize( configuration )
+            @configuration = configuration
+        end
+
+        def visit_Object( object )
+            raise "#{self.class}: Not a visitor for #{object.class}!"
+        end
+
+    end # class VisitorBase
 end