메타프로그래밍

2011년 3월 20일 일요일

enum 형을 만들었다.
메소드 included, const_missing 을 눈여겨볼 것.

module EnumType
    @@enums = {}

    def initialize const, value
        @const = const
        @value = value
    end

    def to_i
        @value
    end

    def to_s
        "#{self.class}::#{@const}"
    end

    def self.included base
        class << base
            def const_missing const
                @@enums.include?(const) ? @@enums[const] : raise(const.to_s)
            end

            def [](value)
                @@enums[value]
            end

            def enum array
                array.each_with_index do |const, value|
                    @@enums[const] = new(const, value)
                    @@enums[value] = @@enums[const]
                end
            end
        end

        base.private_class_method :new
    end
end

class GIRepositoryError
    include EnumType

    enum [:G_IREPOSITORY_ERROR_TYPELIB_NOT_FOUND,
          :G_IREPOSITORY_ERROR_NAMESPACE_MISMATCH,
          :G_IREPOSITORY_ERROR_NAMESPACE_VERSION_CONFLICT,
          :G_IREPOSITORY_ERROR_LIBRARY_NOT_FOUND
    ]
end

p GIRepositoryError[1].object_id
p GIRepositoryError[:G_IREPOSITORY_ERROR_NAMESPACE_MISMATCH].object_id
p GIRepositoryError::G_IREPOSITORY_ERROR_TYPELIB_NOT_FOUND.class
p GIRepositoryError::G_IREPOSITORY_ERROR_TYPELIB_NOT_FOUND
p GIRepositoryError::G_IREPOSITORY_ERROR_NAMESPACE_MISMATCH.object_id
p GIRepositoryError::G_IREPOSITORY_ERROR_NAMESPACE_MISMATCH

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