Comment by codesnik

You don't have to sacrifice that simplicity, actually. (And I insist on that simplicity being a wrong type, it'll bite users of your library basically right away, when they try to use it for anything apart from storage/serialisation)

But you can just give an upgrade path! consider something like this:

  class Address
    attr_accessor :street, :city
  end

  class Person
    attr_accessor :address
  end

  class AddressMapper < Shale::Mapper
    mapped_class Address
    attribute :street, Shale::Type::String
    attribute :city, Shale::Type::String
  end

  class PersonMapper < Shale::Mapper
    mapped_class Person
    attribute :address, AddressMapper
  end

  # use like this
  PersonMapper.from_xml("...."); PersonMapper.to_xml(person)

and then, for _dead_ simplicity, you can add another method generate_mapped_class "Person"

which will define that PORO class for user for extra DRYness. API is basically the same, no repetition, but amount of rewrite with new requirements is drastically less.

I'm not asking you to rewrite your library, and I probably won't write and release mine, just saying that considering future self isn't that hard. And yeah, it's a bit of a rant about ActiveRecord from user of Rails, since 2006.