1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
|
module Uber
module InheritableAttr
def inheritable_attr(name, options={})
instance_eval <<-RUBY, __FILE__, __LINE__ + 1
def #{name}=(v)
@#{name} = v
end
def #{name}
return @#{name} if instance_variable_defined?(:@#{name})
@#{name} = InheritableAttribute.inherit_for(self, :#{name}, #{options})
end
RUBY
end
def self.inherit_for(klass, name, options={})
return unless klass.superclass.respond_to?(name)
value = klass.superclass.send(name) # could be nil
return value if options[:clone] == false
Clone.(value) # this could be dynamic, allowing other inheritance strategies.
end
class Clone
# The second argument allows injecting more types.
def self.call(value, uncloneable=uncloneable())
uncloneable.each { |klass| return value if value.kind_of?(klass) }
value.clone
end
def self.uncloneable
[Symbol, TrueClass, FalseClass, NilClass]
end
end
end
InheritableAttribute = InheritableAttr
end
|
