Rails 2.3.11

[redminele/redminele.git] / ruby / lib / ruby / gems / 1.8 / gems / activesupport-2.3.11 / lib / active_support / core_ext / class / attribute.rb

diff --git a/ruby/lib/ruby/gems/1.8/gems/activesupport-2.3.11/lib/active_support/core_ext/class/attribute.rb b/ruby/lib/ruby/gems/1.8/gems/activesupport-2.3.11/lib/active_support/core_ext/class/attribute.rb
new file mode 100644 (file)
index 0000000..576366e
--- /dev/null
+++ b/ruby/lib/ruby/gems/1.8/gems/activesupport-2.3.11/lib/active_support/core_ext/class/attribute.rb
@@ -0,0 +1,67 @@
+require 'active_support/core_ext/kernel/singleton_class'
+require 'active_support/core_ext/module/remove_method'
+
+class Class
+  # Declare a class-level attribute whose value is inheritable and
+  # overwritable by subclasses:
+  #
+  #   class Base
+  #     class_attribute :setting
+  #   end
+  #
+  #   class Subclass < Base
+  #   end
+  #
+  #   Base.setting = true
+  #   Subclass.setting            # => true
+  #   Subclass.setting = false
+  #   Subclass.setting            # => false
+  #   Base.setting                # => true
+  #
+  # This matches normal Ruby method inheritance: think of writing an attribute
+  # on a subclass as overriding the reader method.
+  #
+  # For convenience, a query method is defined as well:
+  #
+  #   Subclass.setting?           # => false
+  #
+  # Instances may overwrite the class value in the same way:
+  #
+  #   Base.setting = true
+  #   object = Base.new
+  #   object.setting          # => true
+  #   object.setting = false
+  #   object.setting          # => false
+  #   Base.setting            # => true
+  #
+  # To opt out of the instance writer method, pass :instance_writer => false.
+  #
+  #   object.setting = false  # => NoMethodError
+  def class_attribute(*attrs)
+    instance_writer = !attrs.last.is_a?(Hash) || attrs.pop[:instance_writer]
+
+    attrs.each do |name|
+      class_eval <<-RUBY, __FILE__, __LINE__ + 1
+        def self.#{name}() nil end
+        def self.#{name}?() !!#{name} end
+
+        def self.#{name}=(val)
+          singleton_class.class_eval do
+            remove_possible_method(:#{name})
+            define_method(:#{name}) { val }
+          end
+        end
+
+        def #{name}
+          defined?(@#{name}) ? @#{name} : singleton_class.#{name}
+        end
+
+        def #{name}?
+          !!#{name}
+        end
+      RUBY
+
+      attr_writer name if instance_writer
+    end
+  end
+end