kastner · May 13, 2009 14:16 · May 13, 2009 · May 13, 2009 · May 13, 2009
diff --git a/ar_playground_for_so.rb b/ar_playground_for_so.rb
@@ -1,67 +1,71 @@
-    #!/usr/bin/env ruby
-    %w|rubygems active_record irb|.each {|lib| require lib}
-    ActiveSupport::Inflector.inflections.singular("toyota", "toyota")
-    CAR_TYPES = %w|ford buick toyota|
+#!/usr/bin/env ruby
+%w|rubygems active_record irb|.each {|lib| require lib}
+ActiveSupport::Inflector.inflections.singular("toyota", "toyota")
 
-    ActiveRecord::Base.logger = Logger.new(STDOUT)
-    ActiveRecord::Base.establish_connection(
-      :adapter => "sqlite3",
-      :database => ":memory:"
-    )
+ActiveRecord::Base.logger = Logger.new(STDOUT)
+ActiveRecord::Base.establish_connection(
+  :adapter => "sqlite3",
+  :database => ":memory:"
+)
 
-    ActiveRecord::Schema.define do
-      create_table :cars do |t|
-        t.string :name
-      end
+ActiveRecord::Schema.define do
+  create_table :cars do |t|
+    t.string :name
+  end
 
-      create_table :car_to_wheel_table_map, :id => false do |t|
-        t.integer :car_id
-        t.string :wheel_table
-      end
-
-      CAR_TYPES.each do |car_type|
-        create_table "wheels_for_#{car_type.pluralize}" do |t|
-          t.integer :car_id
-          t.string :color
-        end
-      end
-    end
+  create_table :car_to_wheel_table_map, :id => false do |t|
+    t.integer :car_id
+    t.string :wheel_table
+  end
+
+  create_table :wheels_for_fords do |t|
+    t.integer :car_id
+    t.string :color
+  end
+
+  create_table :wheels_for_toyotas do |t|
+    t.integer :car_id
+    t.string :color
+  end
+end
+
+class Wheel < ActiveRecord::Base
+  set_table_name nil
+  belongs_to :car
+end
+
+class CarWheelMap < ActiveRecord::Base
+  set_table_name "car_to_wheel_table_map"
+  belongs_to :car
+end
 
-    CAR_TYPES.each do |car_type|
+class Car < ActiveRecord::Base
+  has_one :car_wheel_map
+  delegate :wheel_table, :to => :car_wheel_map
+
+  def wheels
+    @wheels ||= begin
+      the_klass = "#{wheel_table.classify}Wheel"
       eval <<-END
-        class #{car_type.classify}Wheel < ActiveRecord::Base
-          set_table_name "wheels_for_#{car_type.pluralize}"
+        class #{the_klass} < ActiveRecord::Base
+          set_table_name "wheels_for_#{wheel_table.pluralize}"
           belongs_to :car
         end
       END
+
+      self.class.send(:has_many, "#{wheel_table}_wheels")
+      send "#{wheel_table}_wheels"
     end
+  end
+end
 
-    class Car < ActiveRecord::Base
-      has_one :car_wheel_map
-
-      CAR_TYPES.each do |car_type|
-        has_many "#{car_type}_wheels"
-      end
-
-      delegate :wheel_table, :to => :car_wheel_map
-
-      def wheels
-        send("#{wheel_table}_wheels")
-      end
-    end
-
-    class CarWheelMap < ActiveRecord::Base
-      set_table_name "car_to_wheel_table_map"
-      belongs_to :car
-    end
-
+rav4 = Car.create(:name => "Rav4")
+rav4.create_car_wheel_map(:wheel_table => "toyota")
 
-    rav4 = Car.create(:name => "Rav4")
-    rav4.create_car_wheel_map(:wheel_table => "toyota")
-    rav4.wheels.create(:color => "red")
+fiesta = Car.create(:name => "Fiesta")
+fiesta.create_car_wheel_map(:wheel_table => "ford")
 
-    fiesta = Car.create(:name => "Fiesta")
-    fiesta.create_car_wheel_map(:wheel_table => "ford")
-    fiesta.wheels.create(:color => "green")
+rav4.wheels.create(:color => "red")
+fiesta.wheels.create(:color => "green")
 
-    IRB.start if __FILE__ == $0
+# IRB.start if __FILE__ == $0
diff --git a/snippet.txt → ar_playground_for_so.rb b/snippet.txt → ar_playground_for_so.rb
diff --git a/snippet.txt b/snippet.txt
@@ -0,0 +1,67 @@
+    #!/usr/bin/env ruby
+    %w|rubygems active_record irb|.each {|lib| require lib}
+    ActiveSupport::Inflector.inflections.singular("toyota", "toyota")
+    CAR_TYPES = %w|ford buick toyota|
+
+    ActiveRecord::Base.logger = Logger.new(STDOUT)
+    ActiveRecord::Base.establish_connection(
+      :adapter => "sqlite3",
+      :database => ":memory:"
+    )
+
+    ActiveRecord::Schema.define do
+      create_table :cars do |t|
+        t.string :name
+      end
+
+      create_table :car_to_wheel_table_map, :id => false do |t|
+        t.integer :car_id
+        t.string :wheel_table
+      end
+
+      CAR_TYPES.each do |car_type|
+        create_table "wheels_for_#{car_type.pluralize}" do |t|
+          t.integer :car_id
+          t.string :color
+        end
+      end
+    end
+
+    CAR_TYPES.each do |car_type|
+      eval <<-END
+        class #{car_type.classify}Wheel < ActiveRecord::Base
+          set_table_name "wheels_for_#{car_type.pluralize}"
+          belongs_to :car
+        end
+      END
+    end
+
+    class Car < ActiveRecord::Base
+      has_one :car_wheel_map
+
+      CAR_TYPES.each do |car_type|
+        has_many "#{car_type}_wheels"
+      end
+
+      delegate :wheel_table, :to => :car_wheel_map
+
+      def wheels
+        send("#{wheel_table}_wheels")
+      end
+    end
+
+    class CarWheelMap < ActiveRecord::Base
+      set_table_name "car_to_wheel_table_map"
+      belongs_to :car
+    end
+
+
+    rav4 = Car.create(:name => "Rav4")
+    rav4.create_car_wheel_map(:wheel_table => "toyota")
+    rav4.wheels.create(:color => "red")
+
+    fiesta = Car.create(:name => "Fiesta")
+    fiesta.create_car_wheel_map(:wheel_table => "ford")
+    fiesta.wheels.create(:color => "green")
+
+    IRB.start if __FILE__ == $0