AddInSample.rb

class AddIn
    def initialize name, *version, &block

        @outside = self
        if block_given?
            if block.arity==1
                yield self
            else
                instance_eval &block
            end
        end

        @version = block.call :VersionInfo
        puts @version.inspect

        puts block.inspect
    end

    def method_missing
        # ...
    end

private
    @outside = nil
end
AddIn.new "api.xyzzy.helper".to_s, :X, :Y do
    def VersionInfo
        []
    end
end