Ruby Metaprogramming: Powers

metaprogramming.rb

class Power
    def initialize(x)
        @x = x
    end
    def method_missing(method, *args, &block)
        if /^pow[0-9]+$/ =~ method
            n = /[0-9]+/.match(method.to_s)
            pw = n.to_s.to_i
            eval("def " << method.to_s << "\nres = 1\n(1..#{pw}).each do |c|\nres *= @x\n end\n return res\nend\n")
            eval("self." << method.to_s)
        else
            super.method_missing
        end
    end
end

a = Power.new(29)
puts a.pow3