adding deprecated support for walking ancestor trees

History.txt

@@ -11,6 +11,11 @@
   * Nodes::Node#not factory method added for creating Nodes::Not nodes
   * Added an As node
 
+* Deprecations
+
+  * Support for Subclasses of core classes will be removed in ARel version
+    2.2.0
+
 == 2.0.4
 
 * Bug fixes

lib/arel/visitors/visitor.rb

@@ -13,6 +13,13 @@ module Arel
 
       def visit object
         send DISPATCH[object.class], object
+      rescue NoMethodError
+        warn "visiting #{object.class} via superclass, this will be removed in arel 2.2.0" if $VERBOSE
+        superklass = object.class.ancestors.find { |klass|
+          respond_to?(DISPATCH[klass], true)
+        }
+        DISPATCH[object.class] = DISPATCH[superklass]
+        retry
       end
     end
   end

test/visitors/test_to_sql.rb

@@ -21,6 +21,11 @@ module Arel
         end
       end
 
+      it "should visit string subclass" do
+        @visitor.accept(Class.new(String).new(":'("))
+        @visitor.accept(Class.new(Class.new(String)).new(":'("))
+      end
+
       it "should visit_Class" do
         @visitor.accept(DateTime).must_equal "'DateTime'"
       end