Today I released the Ruby Gem Poro v0.1.0. It is a first working version of an extensible persistence engine. Currently it only has support for MongoDB, but I plan on also supporting SQL and MemCache before going to version 1.0.
You can get it by either calling
gem install poro or by downloading or forking the source on GitHub.
Poro takes a slightly different philosophy from existing gems: Recently I was struck with a thought, in the Ruby world the majority of persistence engines take philosophy of having a base persistence object, and then subclassing that object for everything that needs persistence. This, it seems to me, puts the thought of persistence before the thought of what the object does. In other words, it seems like the chicken before the egg.
In my mind, one should first be worried about what an object does and implementing that. After that, they should be able to transparently add persistence to the object, without actively affecting it.
Poro (which stands for Plain Ol' Ruby Object) tries to take a hands-off approach. It does this by generating and configuring persistence management objects--called contexts--that manage the persistence for a given class. Thus, each class that one wishes to persist has a context sitting off to the side, that can be used (in a functional language like way) to persist an object.
Of course, I realize the convenience of models, so there is a basic model mixin that can be used to your object to add methods like find and save. (In the future, I plan on breaking apart this mixin into several modules that can be included all at once in the same way--as they are now--or in pieces, so that you can add only the pieces you want to use.
At this point, the major thing missing from Poro is testing and tuning. It will probably contain bugs and be slow, but I have plans to use the MongoDB context for a project soon, so it'll should be brought up-to-snuff relatively quickly.