Re: [xml-dev] Re: Re: [xml-dev] SAX/Java Proposed Changes

Elliotte Rusty Harold <[email protected]> Fri, 5 Mar 2004 13:41:30 -0500
Newsgroups gmane.text.xml.sax.devel,gmane.text.xml.devel
Message-ID <p0601020dbc6e791ad618@[192.168.254.4]>
At 12:47 PM -0500 3/5/04, Karl Waclawek wrote:

>The question is: why can the exception argument passed to fataError()
>wrap another exeption then?


Because it's sometimes useful to do so. For instance, the parser 
might detect a well-formedness error when Reader.read throws a 
CharacterConversionException. It could then stick this exception into 
the exception field of the SAXException, so it could be further 
inspected, in a debugger for example. The goal here is to provide 
additional information about the cause of one exceptional condition, 
not to chain together a bunch of exceptions that each represent a 
different error in the same document.

In Java 1.4 all exceptions, in fact all throwables, can have nested 
exceptions. This is a general pattern that makes debugging easier. It 
is not meant stuff several exceptional conditions into one object. 
Instead it is meant to provide different views of a single 
exceptional condition.

-- 

   Elliotte Rusty Harold
   [email protected]
   Effective XML (Addison-Wesley, 2003)
   http://www.cafeconleche.org/books/effectivexml
   http://www.amazon.com/exec/obidos/ISBN%3D0321150406/ref%3Dnosim/cafeaulaitA


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