Introduce builders for each of CID versions

[Mingela]

Now there is a CID V0 used by default in CidBuilders. But why not to use V1 one?

go-merkledag/node.go

Lines 66 to 83 in d532cda

	// CidBuilder returns the CID Builder for this ProtoNode, it is never nil
	func (n *ProtoNode) CidBuilder() cid.Builder {
	if n.builder == nil {
	n.builder = v0CidPrefix
	}
	return n.builder
	}
	// SetCidBuilder sets the CID builder if it is non nil, if nil then it
	// is reset to the default value
	func (n *ProtoNode) SetCidBuilder(builder cid.Builder) {
	if builder == nil {
	n.builder = v0CidPrefix
	} else {
	n.builder = builder.WithCodec(cid.DagProtobuf)
	n.cached = cid.Undef
	}
	}

And probably a client do not even guess what's going inside there methods. How about switching to an interface providing builders for each version etc?

[Stebalien]

We still use CIDv0 by default for dag-pb to avoid changing the hashes.

And probably a client do not even guess what's going inside there methods. How about switching to an interface providing builders for each version etc?

I'm not sure what you're asking. You can switch to a CIDv1 builder by calling n.SetCidBuilder(&cid.V1Builder{Codec: cid.DatProtobuf, mh.SHA2_256, MhLength: -1}).