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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
#
# some_person.age
# => 25
# some_person.age = 26
# some_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 = nil, &block)
raise 'Default value or block required' unless !default.nil? || block
define_method(sym, block_given? ? block : Proc.new { default })
module_eval(<<-EVAL, __FILE__, __LINE__)
def #{sym}=(value)
class << self; attr_reader :#{sym} end
@#{sym} = value
end
EVAL
end
end
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