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require 'active_support/core_ext/object/blank'
class Class
def superclass_delegating_reader(*names)
class_name_to_stop_searching_on = superclass.name.blank? ? "Object" : superclass.name
names.each do |name|
class_eval(<<-EOS, __FILE__, __LINE__ + 1)
def self.#{name} # def self.only_reader
if defined?(@#{name}) # if defined?(@only_reader)
@#{name} # @only_reader
elsif superclass < #{class_name_to_stop_searching_on} && # elsif superclass < Object &&
superclass.respond_to?(:#{name}) # superclass.respond_to?(:only_reader)
superclass.#{name} # superclass.only_reader
end # end
end # end
def #{name} # def only_reader
self.class.#{name} # self.class.only_reader
end # end
def self.#{name}? # def self.only_reader?
!!#{name} # !!only_reader
end # end
def #{name}? # def only_reader?
!!#{name} # !!only_reader
end # end
EOS
end
end
def superclass_delegating_writer(*names, &block)
names.each do |name|
class_eval(<<-EOS, __FILE__, __LINE__ + 1)
def self.#{name}=(value) # def self.property=(value)
@#{name} = value # @property = value
end # end
EOS
self.send("#{name}=", yield) if block_given?
end
end
# 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.
def superclass_delegating_accessor(*names, &block)
superclass_delegating_reader(*names)
superclass_delegating_writer(*names, &block)
end
end
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