On 30/12/2008, at 1:40 AM, Robert Dionne wrote:
With respect to a meta structure, I was going to make this comment
yesterday as I think Geir was arguing for this:
It seems to me that occam's razor argues for the simplicity of a
single JSON doc, rather that a "metadoc" envelope that contains
another JSON doc embedded in it. It's not clear to me that creating
this separation of concerns buys anything at all. The use of an
underscore to designate distinguished fields at the top level is a
fairly easy convention to get your arms around.
That's not actually the issue. The issue is about having a single
name, and not inventing a namespace technique for json docs. The
choices are:
1. The current scheme of prepending _ to atom names when the atom is
used inside a document. Con is the breakage of name identity, which
has technical consequences as well as cognitive ones. Does the rule
only apply at the top level of a document? What about future injected
metadata that has internal structure?
2. Use '_' for all atoms, inside and outside documents. Con is the
noise of extra underscores everywhere.
3. Don't use underscores inside documents - for id and rev at least,
this wouldn't seem to be a big issue, but isn't future-proof if you
want to handle other injected fields.
4. Use '_' for atoms that have to be injected, and make the name BE
the '_' form. Con is that you have to decide in advance if an atom is
going to ever be injected.
5. Use a '_meta' wrapper for the metadata. I don't see any technical
cons, and IMO is by far the cleanest model. Name identity is
preserved, it's arbitrarily extensible without scalability concerns,
and is structural rather than lexical.
IMO option 5 is the best and cleanest solution.
Antony Blakey
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