1 # Retain for backward compatibility. Methods are now included in Class.
2 module ClassInheritableAttributes # :nodoc:
3 end
4
5 # Allows attributes to be shared within an inheritance hierarchy, but where each descendant gets a copy of
6 # their parents' attributes, instead of just a pointer to the same. This means that the child can add elements
7 # to, for example, an array without those additions being shared with either their parent, siblings, or
8 # children, which is unlike the regular class-level attributes that are shared across the entire hierarchy.
9 class Class # :nodoc:
10 def class_inheritable_reader(*syms)
11 syms.each do |sym|
12 next if sym.is_a?(Hash)
13 class_eval <<-EOS
14 def self.#{sym} # def self.before_add_for_comments
15 read_inheritable_attribute(:#{sym}) # read_inheritable_attribute(:before_add_for_comments)
16 end # end
17 #
18 def #{sym} # def before_add_for_comments
19 self.class.#{sym} # self.class.before_add_for_comments
20 end # end
21 EOS
22 end
23 end
24
25 def class_inheritable_writer(*syms)
26 options = syms.extract_options!
27 syms.each do |sym|
28 class_eval <<-EOS
29 def self.#{sym}=(obj) # def self.color=(obj)
30 write_inheritable_attribute(:#{sym}, obj) # write_inheritable_attribute(:color, obj)
31 end # end
32 #
33 #{" #
34 def #{sym}=(obj) # def color=(obj)
35 self.class.#{sym} = obj # self.class.color = obj
36 end # end
37 " unless options[:instance_writer] == false } # # the writer above is generated unless options[:instance_writer] == false
38 EOS
39 end
40 end
41
42 def class_inheritable_array_writer(*syms)
43 options = syms.extract_options!
44 syms.each do |sym|
45 class_eval <<-EOS
46 def self.#{sym}=(obj) # def self.levels=(obj)
47 write_inheritable_array(:#{sym}, obj) # write_inheritable_array(:levels, obj)
48 end # end
49 #
50 #{" #
51 def #{sym}=(obj) # def levels=(obj)
52 self.class.#{sym} = obj # self.class.levels = obj
53 end # end
54 " unless options[:instance_writer] == false } # # the writer above is generated unless options[:instance_writer] == false
55 EOS
56 end
57 end
58
59 def class_inheritable_hash_writer(*syms)
60 options = syms.extract_options!
61 syms.each do |sym|
62 class_eval <<-EOS
63 def self.#{sym}=(obj) # def self.nicknames=(obj)
64 write_inheritable_hash(:#{sym}, obj) # write_inheritable_hash(:nicknames, obj)
65 end # end
66 #
67 #{" #
68 def #{sym}=(obj) # def nicknames=(obj)
69 self.class.#{sym} = obj # self.class.nicknames = obj
70 end # end
71 " unless options[:instance_writer] == false } # # the writer above is generated unless options[:instance_writer] == false
72 EOS
73 end
74 end
75
76 def class_inheritable_accessor(*syms)
77 class_inheritable_reader(*syms)
78 class_inheritable_writer(*syms)
79 end
80
81 def class_inheritable_array(*syms)
82 class_inheritable_reader(*syms)
83 class_inheritable_array_writer(*syms)
84 end
85
86 def class_inheritable_hash(*syms)
87 class_inheritable_reader(*syms)
88 class_inheritable_hash_writer(*syms)
89 end
90
91 def inheritable_attributes
92 @inheritable_attributes ||= EMPTY_INHERITABLE_ATTRIBUTES
93 end
94
95 def write_inheritable_attribute(key, value)
96 if inheritable_attributes.equal?(EMPTY_INHERITABLE_ATTRIBUTES)
97 @inheritable_attributes = {}
98 end
99 inheritable_attributes[key] = value
100 end
101
102 def write_inheritable_array(key, elements)
103 write_inheritable_attribute(key, []) if read_inheritable_attribute(key).nil?
104 write_inheritable_attribute(key, read_inheritable_attribute(key) + elements)
105 end
106
107 def write_inheritable_hash(key, hash)
108 write_inheritable_attribute(key, {}) if read_inheritable_attribute(key).nil?
109 write_inheritable_attribute(key, read_inheritable_attribute(key).merge(hash))
110 end
111
112 def read_inheritable_attribute(key)
113 inheritable_attributes[key]
114 end
115
116 def reset_inheritable_attributes
117 @inheritable_attributes = EMPTY_INHERITABLE_ATTRIBUTES
118 end
119
120 private
121 # Prevent this constant from being created multiple times
122 EMPTY_INHERITABLE_ATTRIBUTES = {}.freeze unless const_defined?(:EMPTY_INHERITABLE_ATTRIBUTES)
123
124 def inherited_with_inheritable_attributes(child)
125 inherited_without_inheritable_attributes(child) if respond_to?(:inherited_without_inheritable_attributes)
126
127 if inheritable_attributes.equal?(EMPTY_INHERITABLE_ATTRIBUTES)
128 new_inheritable_attributes = EMPTY_INHERITABLE_ATTRIBUTES
129 else
130 new_inheritable_attributes = inheritable_attributes.inject({}) do |memo, (key, value)|
131 memo.update(key => value.duplicable? ? value.dup : value)
132 end
133 end
134
135 child.instance_variable_set('@inheritable_attributes', new_inheritable_attributes)
136 end
137
138 alias inherited_without_inheritable_attributes inherited
139 alias inherited inherited_with_inheritable_attributes
140 end