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class Module
# Declare an attribute accessor with an initial default return value.
#
# To give attribute <tt>:age</tt> the initial value <tt>25</tt>:
#
# class Person
# attr_accessor_with_default :age, 25
# end
#
# person = Person.new
# person.age # => 25
#
# person.age = 26
# person.age # => 26
#
# To give attribute <tt>:element_name</tt> a dynamic default value, evaluated
# in scope of self:
#
# attr_accessor_with_default(:element_name) { name.underscore }
#
def attr_accessor_with_default(sym, default = Proc.new)
define_method(sym, block_given? ? default : Proc.new { default })
module_eval(<<-EVAL, __FILE__, __LINE__ + 1)
def #{sym}=(value) # def age=(value)
class << self; attr_accessor :#{sym} end # class << self; attr_accessor :age end
@#{sym} = value # @age = value
end # end
EVAL
end
end
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