I don't think you should rule out using bidirectional refs because
everyone is busy -- although there may be other reasons to rule them
out. We use bidirectional refs in so many places that not being familiar
with them is a pretty serious handicap. There are lots of examples in
the code that uses them and I suspect none of us is really too busy to
answer a question about them now and then.
John
Alec Flett wrote:
John Anderson wrote:
As it turns out there are lots of ways to do this. The "kind query"
scheme you're proposing is just one way we've discussed doing it.
Another interesting possibility we've discussed is using
bidirectional references on ref collections, e.g. assigning an
attribute hooks the a corresponding reference on the other end of a
system collection that can be used to find the registered things.
Another possibility we've discusses is executing code at parcel load
time -- which seems not quite as nice as the two previous data driven
schemes. Finally, none of these deal with the possibility of allowing
the user to participate in choosing between registered alternatives,
e.g. choosing between alternative viewers for a particular datatype.
I agree that a data-driven mechanism is the way to go - at least in
the general case. Personally I think that the bi-directional reference
with a container system seems like our best bet - my "Kind" mechanism
is not ideal. (and I've done code-executing-at-startup and it ends up
being pretty ugly)
I think in the case of the sidebar, however, it would be nice to
register a new item collection as well as an optional viewer (today
we only have two, table and calendar). However, all this is beyond
the scope of 0.5.
That's not a problem I'm trying to solve for 0.5 anyway... so that's good.
This is clearly an area that needs to be fleshed out post 0.5, with
input from UI, design and by considering our other registration
needs, so I think it's premature to add it as described without
further discussion.
I need it for ZaoBao as a proof-of-concept of extensions actually
working in Chandler without being hard coded in. Given the realities
of 0.5 (such as me not knowing enough about references in the
repository or the parcel loader, and other folks being busy) I'd like
to move forward with the "Kind" mechanism and discuss something better
(i.e. the bidirectional reference mechanism) as well as the issue of
user-intervention, for 0.6.
Alec
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