State should not depend on the API server

[William Reade]

On Thu, Sep 11, 2014 at 3:35 PM, Nate Finch <nate.finch at canonical.com> wrote:
> I don't see how having different identical structs that are updated
> simultaneously in any way prevents any problems with compatibility.

If we're updating those structs simultaneously, we're completely
missing the point. Once we've defined a pure-data struct that might be
persisted or sent over the wire we *must not change that struct* -- if
we want to send or store different data, we need a new struct.

> Maybe I'm missing something from the proposal, but it seems like this just
> adds busywork without actually solving any problems that weren't caused by
> incorrect use of the code in the first place.

Isn't that tautological? AFAICS, storing a charm.Meta (or a
params.anything) directly in the DB *is* incorrect use of the code,
but nobody realises that until it's too late: that is the problem, and
that's what we're addressing.

> Separation of logic is absolutely a good thing.  Separation of data is not
> nearly so useful.

It's harder than you might think to separate the data from the logic
that acts on it ;).

Cheers
William