32 lines
1 KiB
Ruby
32 lines
1 KiB
Ruby
class Module
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# Declare an attribute accessor with an initial default return value.
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#
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# To give attribute <tt>:age</tt> the initial value <tt>25</tt>:
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#
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# class Person
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# attr_accessor_with_default :age, 25
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# end
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#
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# some_person.age
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# => 25
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# some_person.age = 26
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# some_person.age
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# => 26
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#
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# To give attribute <tt>:element_name</tt> a dynamic default value, evaluated
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# in scope of self:
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#
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# attr_accessor_with_default(:element_name) { name.underscore }
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#
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def attr_accessor_with_default(sym, default = nil, &block)
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raise 'Default value or block required' unless !default.nil? || block
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define_method(sym, block_given? ? block : Proc.new { default })
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module_eval(<<-EVAL, __FILE__, __LINE__ + 1)
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def #{sym}=(value) # def age=(value)
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class << self; attr_reader :#{sym} end # class << self; attr_reader :age end
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@#{sym} = value # @age = value
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end # end
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EVAL
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end
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end
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