1 # These class attributes behave something like the class
2 # inheritable accessors. But instead of copying the hash over at
3 # the time the subclass is first defined, the accessors simply
4 # delegate to their superclass unless they have been given a
5 # specific value. This stops the strange situation where values
6 # set after class definition don't get applied to subclasses.
7 class Class
8 def superclass_delegating_reader(*names)
9 class_name_to_stop_searching_on = self.superclass.name.blank? ? "Object" : self.superclass.name
10 names.each do |name|
11 class_eval <<-EOS
12 def self.#{name} # def self.only_reader
13 if defined?(@#{name}) # if defined?(@only_reader)
14 @#{name} # @only_reader
15 elsif superclass < #{class_name_to_stop_searching_on} && # elsif superclass < Object &&
16 superclass.respond_to?(:#{name}) # superclass.respond_to?(:only_reader)
17 superclass.#{name} # superclass.only_reader
18 end # end
19 end # end
20 def #{name} # def only_reader
21 self.class.#{name} # self.class.only_reader
22 end # end
23 def self.#{name}? # def self.only_reader?
24 !!#{name} # !!only_reader
25 end # end
26 def #{name}? # def only_reader?
27 !!#{name} # !!only_reader
28 end # end
29 EOS
30 end
31 end
32
33 def superclass_delegating_writer(*names)
34 names.each do |name|
35 class_eval <<-EOS
36 def self.#{name}=(value) # def self.only_writer=(value)
37 @#{name} = value # @only_writer = value
38 end # end
39 EOS
40 end
41 end
42
43 def superclass_delegating_accessor(*names)
44 superclass_delegating_reader(*names)
45 superclass_delegating_writer(*names)
46 end
47 end