Define a instance method with a class method crazy-meta-ness

instance-class-def.rb

class Base
  def self.method_missing(sym, *args, &block)
    send :define_method, sym, (args.empty? ? block : args[0].to_proc)
  end
end

class A < Base
  intify   :to_i
  floatify :to_f
end

class B < Base
  die {|n| 'DIE!' * n }
end

a = A.new
p a.intify '123'
#=> 123
p a.floatify '123'
#=> 123.0

b = B.new
p b.die 5
#=> 'DIE!DIE!DIE!DIE!DIE!'