Added availability of class inheritable attributes to the masses #477 [bitsweat]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@412 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activesupport/CHANGELOG

@@ -1,3 +1,21 @@
+* Added availability of class inheritable attributes to the masses #477 [bitsweat]
+
+    class Foo
+      class_inheritable_reader :read_me
+      class_inheritable_writer :write_me
+      class_inheritable_accessor :read_and_write_me
+      class_inheritable_array :read_and_concat_me
+      class_inheritable_hash :read_and_update_me
+    end
+
+    # Bar gets a clone of (not a reference to) Foo's attributes.
+    class Bar < Foo
+    end
+
+    Bar.read_and_write_me == Foo.read_and_write_me
+    Bar.read_and_write_me = 'bar'
+    Bar.read_and_write_me != Foo.read_and_write_me
+
 * Added Inflections as an extension on String, so Inflector.pluralize(Inflector.classify(name)) becomes name.classify.pluralize #476 [bitsweat]
 
 * Added Byte operations to Numeric, so 5.5.megabytes + 200.kilobytes #461 [Marcel Molina]

activesupport/lib/class_inheritable_attributes.rb

@@ -1,46 +1,117 @@
+# Retain for backward compatibility.  Methods are now included in Class.
+module ClassInheritableAttributes # :nodoc:
+end
+
 # Allows attributes to be shared within an inheritance hierarchy, but where each descendant gets a copy of
 # their parents' attributes, instead of just a pointer to the same. This means that the child can add elements
 # to, for example, an array without those additions being shared with either their parent, siblings, or
 # children, which is unlike the regular class-level attributes that are shared across the entire hierarchy.
-module ClassInheritableAttributes # :nodoc:
-  def self.append_features(base)
-    super
-    base.extend(ClassMethods)
+class Class # :nodoc:
+  def class_inheritable_reader(*syms)
+    syms.each do |sym|
+      class_eval <<-EOS
+        def self.#{sym}
+          read_inheritable_attribute(:#{sym})
+        end
+
+        def #{sym}
+          self.class.#{sym}
+        end
+      EOS
+    end
+  end
+
+  def class_inheritable_writer(*syms)
+    syms.each do |sym|
+      class_eval <<-EOS
+        def self.#{sym}=(obj)
+          write_inheritable_attribute(:#{sym}, obj)
+        end
+
+        def #{sym}=(obj)
+          self.class.#{sym} = obj
+        end
+      EOS
+    end
+  end
+
+  def class_inheritable_array_writer(*syms)
+    syms.each do |sym|
+      class_eval <<-EOS
+        def self.#{sym}=(obj)
+          write_inheritable_array(:#{sym}, obj)
+        end
+
+        def #{sym}=(obj)
+          self.class.#{sym} = obj
+        end
+      EOS
+    end
+  end
+
+  def class_inheritable_hash_writer(*syms)
+    syms.each do |sym|
+      class_eval <<-EOS
+        def self.#{sym}=(obj)
+          write_inheritable_hash(:#{sym}, obj)
+        end
+
+        def #{sym}=(obj)
+          self.class.#{sym} = obj
+        end
+      EOS
+    end
+  end
+
+  def class_inheritable_accessor(*syms)
+    class_inheritable_reader(*syms)
+    class_inheritable_writer(*syms)
+  end
+
+  def class_inheritable_array(*syms)
+    class_inheritable_reader(*syms)
+    class_inheritable_array_writer(*syms)
+  end
+
+  def class_inheritable_hash(*syms)
+    class_inheritable_reader(*syms)
+    class_inheritable_hash_writer(*syms)
+  end
+
+  def inheritable_attributes
+    @inheritable_attributes ||= {}
   end
   
-  module ClassMethods # :nodoc:
-    @@classes ||= {}
-    
-    def inheritable_attributes
-      @@classes[self] ||= {}
-    end
-    
-    def write_inheritable_attribute(key, value)
-      inheritable_attributes[key] = value
-    end
-    
-    def write_inheritable_array(key, elements)
-      write_inheritable_attribute(key, []) if read_inheritable_attribute(key).nil?
-      write_inheritable_attribute(key, read_inheritable_attribute(key) + elements)
-    end
-
-    def write_inheritable_hash(key, hash)
-      write_inheritable_attribute(key, {}) if read_inheritable_attribute(key).nil?
-      write_inheritable_attribute(key, read_inheritable_attribute(key).merge(hash))
-    end
-
-    def read_inheritable_attribute(key)
-      inheritable_attributes[key]
-    end
-    
-    def reset_inheritable_attributes
-      inheritable_attributes.clear
-    end
-
-    private 
-      def inherited(child)
-        @@classes[child] = inheritable_attributes.dup
-      end
-   
+  def write_inheritable_attribute(key, value)
+    inheritable_attributes[key] = value
   end
+  
+  def write_inheritable_array(key, elements)
+    write_inheritable_attribute(key, []) if read_inheritable_attribute(key).nil?
+    write_inheritable_attribute(key, read_inheritable_attribute(key) + elements)
+  end
+
+  def write_inheritable_hash(key, hash)
+    write_inheritable_attribute(key, {}) if read_inheritable_attribute(key).nil?
+    write_inheritable_attribute(key, read_inheritable_attribute(key).merge(hash))
+  end
+
+  def read_inheritable_attribute(key)
+    inheritable_attributes[key]
+  end
+  
+  def reset_inheritable_attributes
+    inheritable_attributes.clear
+  end
+
+  private 
+    def inherited_with_inheritable_attributes(child)
+      inherited_without_inheritable_attributes(child) if respond_to?(:inherited_without_inheritable_attributes)
+      child.instance_variable_set('@inheritable_attributes', inheritable_attributes.dup)
+    end
+
+    if respond_to?(:inherited)
+      alias_method :inherited_without_inheritable_attributes, :inherited
+    end
+    alias_method :inherited, :inherited_with_inheritable_attributes
 end