module Hashie::Extensions::MethodOverridingWriter

def already_overridden?(name)
  method?("__#{name}")
end

def convert_key(key)
  key.to_s
end

def method_missing(name, *args)
  if args.size == 1 && name.to_s =~ /(.*)=$/
    key = Regexp.last_match[1]
    redefine_method(key) if method?(key) && !already_overridden?(key)
    return self[convert_key(key)] = args.first
  end
  super
end

def respond_to_missing?(name, include_private = false)
  return true if name.to_s.end_with?('=')
  super
end