Right now the Cid type is:

type Cid struct {
    version uint64
    codec   uint64
    hash    mh.Multihash
}

The internals are not exposed but it is expected to be passed around by pointer which in a way exposes some of the implementation details. For example in #3 I suggested we use a more compact structural representation and I think @Stebalien is suggesting to a serialized string instead. The best representation may be debatable, but either change will require that the Cid no longer be passed around by a pointer. We may even decide that a Cid is better represented by an interface and some point.

So for now may I suggestion that we start passing around the Cid type directly and change the representation to.

type Cid struct {
    *cid
} 
type cid struct {
    version uint64
    codec   uint64
    hash    mh.Multihash
}

This will then give us the freedom to try different internal representations without making requiring any API changes.

@whyrusleeping @Stebalien thoughts?