Errors and exceptions

[Tuomas Lukka <lukka@xxxxxxxxxx>]

We discussed this a bit in the last Jyväskylä group meeting: seeing
as the Java API will be with us for a while, we might try to make
it work well.

So we should classify the exceptional conditions as exceptions and errors.
As background, Java requires explicit "throws" clauses for exceptions, but
not for errors. Currently most things that go wrong in ZZ are errors in
order to avoid "throws" clauses everywhere.

The following exceptions are the most important classes:

	ConnectionWouldBreak - an attempted connection would break 
		an existing one

		- exception?

	I/O - file I/O and format errors
		- error?
			- these would be difficult to react to
			  anywhere but globally.

	InfiniteLoop
		- exception?

Opinions?

	Tuomas