error trapping

[David Brownell]

james anderson wrote:
> 
> the xml parser with cl-http signals exceptions. lisp's control model permits
> the handler to execute in the dynamic context of the parser which would permit
> the caller to decide what to do. on the other hand, i've yet to implement any
> continuations: i terminate the parser, but other options are possible.
> 
> one intrinsic problem with java parsers is that the java control model forces
> exceptions to unwind from the initiator's dynamic  context before the handler
> obtains control. this would mean that a callback interface would have to be
> proposed, ratified, and implemented. i recall discussions of such a thing when
> sax started, but the recollection is vague.

SAX has an "ErrorHandler" object which is used to decide how to handle the
error ... throwing an exception is the default for fatal (WF) errors, but
for all other errors (and warnings) the default is to continue processing.

So the effect is similar to the Lisp approach you mentioned, except that the
context for the "continue?" decision is less dynamic.

- Dave

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