Re: [xtm-wg] A challenge on "the graph"

[Lars Marius Garshol <larsga@garshol.priv.no>]

* W. Eliot Kimber
| 
| I'm not suggesting we do the API first, only that we aren't done until
| we have defined an API. To do it right, you must define the model first
| and then the API that exposes that model. On that we appear to agree
| completely.

We do.
 
| I don't see a problem with an API saying "here's how you modify a
| topic map" and leaving it at that. In a single-user system, that is
| sufficient and there are no concurrency issues.

I explained this already. If you offer any form of iterators, even
index-based enumeration, and you will have to offer this, you must
carefully specify what happens when the collection being iterated over
is being changed.

It happens often, even in single-user, single-thread applications,
that collections are modified as they are being iterated over.
Believe me, I've stumbled over this enough times to know that it
happens.

This is a side issue, though. As long as we agree that the data model
can be published first and the the API afterwards this doesn't matter
at all.
 
| For example, the DOM could be applied in a multi-user environment
| and raise exactly the same concurrency issues you cite, but the DOM
| doesn't have to say anything about concurrency and it doesn't.
 
During the DOM design there was a tremendous amount of argument over
how to deal with iterators, and the resulting design does indeed deal
with that precise issue.

| I think that Lars and I are in fact pretty much in complete agreement
| except on the issue of using UML as the modeling language.

We are.

--Lars M.


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