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delegating_attributes.rb
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delegating_attributes.rb
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# These class attributes behave something like the class
# inheritable accessors. But instead of copying the hash over at
# the time the subclass is first defined, the accessors simply
# delegate to their superclass unless they have been given a
# specific value. This stops the strange situation where values
# set after class definition don't get applied to subclasses.
class Class
def superclass_delegating_reader(*names)
class_name_to_stop_searching_on = self.superclass.name.blank? ? "Object" : self.superclass.name
names.each do |name|
class_eval <<-EOS
def self.#{name}
if defined?(@#{name})
@#{name}
elsif superclass < #{class_name_to_stop_searching_on} && superclass.respond_to?(:#{name})
superclass.#{name}
end
end
def #{name}
self.class.#{name}
end
def self.#{name}?
!!#{name}
end
def #{name}?
!!#{name}
end
EOS
end
end
def superclass_delegating_writer(*names)
names.each do |name|
class_eval <<-EOS
def self.#{name}=(value)
@#{name} = value
end
EOS
end
end
def superclass_delegating_accessor(*names)
superclass_delegating_reader(*names)
superclass_delegating_writer(*names)
end
end