SAX: Error Reporting (question 4 of 10)

Paul Prescod papresco at technologist.com
Sun Jan 4 02:15:50 GMT 1998


David Megginson wrote:
> 
> - Java already has throwable errors and exceptions, which provide a
>   more elegant method for error reporting.

I don't think that they are very elegant this case. By the time the
exception is caught, the continuation (stack and stack pointer, for
non-Scheme programmers) has been lost. Continuing the parse is
problematic (as you pointed out).
 
> We can have the following default implementations in XmlAppBase:

As long as the default implementations in XmlAppBase are only 1 line,
then I don't think DavidO has much to worry about for implementors in
other languages.

> If we decide to implement startEntity() and endEntity(), then the
> systemID argument to these methods will be redundant (the current URI
> will always be known); in that case, should we still leave the
> systemID argument in for convenience?

I would prefer a getCurrentLocation() method that can be called
anywhere.
 
> Do we need a 'column' argument as well as a 'line' argument, or is
> 'line' enough?  I don't know if all parsers track the current column,
> but we could define a behaviour for those that do not (such as
> reporting the column as -1).

I'm not big on that last idea. It adds complexity to the spec. and to
applications. Careless implementors will report errors on line "-1" or
perhaps crash.

Either require it or don't. I would vote to require it.

 Paul Prescod
--
http://itrc.uwaterloo.ca/~papresco

Art is always at peril in universities, where there are so many people, 
young and old, who love art less than argument, and dote upon a text 
that provides the nutritious pemmican on which scholars love to chew. 
				-- Robertson Davies in "The Cunning Man"



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